Title of Invention

A RECOMBINANT E.COLI

Abstract The present invention provides an improved method for the biological production of 1,3-propanediol from a fermentable carbon source in a single microorganism. In one aspect of the present invention, an improved process for the conversion of glucose to 1,3-propanediol is achieved by the use of an E. coli transformed with the Klebsiella pneumoniae dha regulon genes dhaR, orfY, dhaT, orfX, orfW, dhaB1, dhaB2, dhaB3, and orfZ, all these genes arranged in the same genetic organization as found in wild type Klebsiella pneumoniae. In another aspect of the present invention, an improved process for the production of 1,3-propanediol from glucose using a recombinant E. coli containing genes encoding a G3PDH, a G3P phosphatase, a dehydratase, and a dehydratase reactivation factor compared to an identical process using a recombinant E. coli containing genes encoding a G3PDH, a G3P phosphatase, a dehydratase, a dehydratase reactivation factor and a 1,3-propanediol oxidoreductase (dhaT). The dramatically improved process relies on the presence in E. Coli of a gene encoding a non-specific catalytic activity sufficient to convert 3-hydroxypropionaldehyde to 1,3-propanediol.
Full Text FORM 2
THE PATENTS ACT, 1970
[39 OF 1970]
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See Section 10; rule 13]
" A MICROORGANISM TRANSFORMED WITH A CHIMERIC GENE"
E.I. DU PONT DE NEMOURS AND COMPANY, a Delaware corporation, of 1007 Market Street, Wilmington, Delaware 19898 , United States of America, and GENENCOR INTERNATIONAL INC., of 925 Page Mill Road, Palo Alto, CA 94303, United States of America,
The following specification particularly describes the nature of the invention and the manner in which it is to be performed:-

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TITLE
PROCESS FOR THE BIOLOGICAL PRODUCTION
OF U-PROPANEDIOL WITH HIGH TITER
FIELD OF INVENTION
5 This invention comprises process for the bioconversion of a fermentable
carbon source to 1,3-propanediol by a single microorganism.
BACKGROUND
1,3-Propanediol is a monomer having potential utility in the production of
polyester fibers and the manufacture of polyurethanes and cyclic compounds.
10 A variety of chemical routes to 1,3-propanediol are known. For example
ethylene oxide may be converted to 1,3-propanediol over a catalyst in the presence
of phosphine, water, carbon monoxide, hydrogen and an acid, by the catalytic
solution phase hydration of acrolein followed by reduction, or from compounds
such as glycerol, reacted in the presence of carbon monoxide and hydrogen over 15 catalysts having atoms from group VIII of the periodic table. Although it is
possible to generate 1,3-propanediol by these methods, they are expensive and
generate waste streams containing environmental pollutants.
It has been known for over a century that 1,3-propanediol can be produced
from the fermentation of glycerol. Bacterial strains able to produce
20 1,3-propanediol have been found, for example, in the groups Citrobacter,
Clostridium, Enterobacter, Ilyobacter, Klebsiella, Lactobacillus, and Pelobacter.
In each case studied, glycerol is converted to 1,3-propanediol in a two step,
enzyme catalyzed reaction sequence. In the first step, a dehydratase catalyzes the
conversion of glycerol to 3-hydroxypropionaldehyde (3-HPA) and water,
25 Equation 1. In the second step, 3-HPA is reduced to 1,3-propanediol by a
NAD+-linked oxidoreductase, Equation 2. The 1,3-propanediol is not
metabolized further and, as a result,
Glycerol -► 3-HPA + H20 (Equation 1)
30 3-HPA + NADH + H+ -> 1,3-Propanediol + NAD+ (Equation 2)
accumulates in the media. The overall reaction consumes a reducing equivalent in
the form of a cofactor, reduced β-nicotinamide adenine dinucleotide (NADH),
which is oxidized to nicotinamide adenine dinucleotide (NAD+).
35 In Klebsiella pneumonia, Citrobacter freundii, and Clostridium
pasteurianum, the genes encoding the three structural subunits of glycerol dehydratase {dhaBl-3 or dhaB, C andE) are located adjacent to a gene encoding a specific 1,3-propanediol oxidoreductase (dhaT) (see Figure 1). Although the
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genetic organization differs somewhat among these microorganisms, these genes are clustered in a group which also comprises orfX and or/Z (genes encoding a
dehydratase reactivation factor for glycerol dehydratase), as well as orfYand orfw
(genes of unknown function). The specific 1,3-propanediol oxidoreductases
5 (dhaTs) of these microorganisms are known to belong to the family of type III alcohol dehydrogenases; each exhibits a conserved iron-binding motif and has a preference for the NAD+/NADH linked interconversion of 1,3-propandiol and 3-HPA. However, the NAD+/NADH linked interconversion of 1,3-propandiol and 3-HPA is also catalyzed by alcohol dehydrogenases which are not specifically
10 linked to dehydratase enzymes (for example, horse liver and baker's yeast alcohol dehydrogenases (B.C. 1.1.1.1)), albeit with less efficient kinetic parameters. Glycerol dehydratase (E.C. 4.2.1.30) and diol [1,2-propanediol] dehydratase (E.C. 4.2.1.28) are related but distinct enzymes that are encoded by distinct genes. Diol dehydratase genes from Klebsiella oxytoca and Salmonella typhimurium are
15 similar to glycerol dehydratase genes and are clustered in a group which
comprises genes analogous to orpC and or/Z (Daniel et al., FEMS Microbiol. Rev. 22, 553 (1999); Toraya and Mori, J. Biol. Chem. 274, 3372 (1999); GenBank AF026270).
The production of 1,3-propanediol from glycerol is generally performed
20 under anaerobic conditions using glycerol as the sole carbon source and in the absence of other exogenous reducing equivalent acceptors. Under these conditions, in e.g., strains of Citrobacter, Clostridium, and Klebsiella, a parallel pathway for glycerol operates which first involves oxidation of glycerol to dihydroxyacetone (DHA) by a NAD+- (or NADP+-) linked glycerol
25 dehydrogenase, Equation 3. The DHA, following phosphorylation to dihydroxyacetone phosphate (DHAP) by a DHA kinase (Equation 4),
Glycerol + NAD+ -> DHA + NADH + H+ (Equation 3)
DHA + ATP -* DHAP + ADP (Equation 4)
30
becomes available for biosynthesis and for supporting ATP generation via e.g.,
glycolysis. In contrast to the 1,3-propanediol pathway, this pathway may provide carbon and energy to the cell and produces rather than consumes NADH.
In Klebsiella pneumoniae and Citrobacter freundii, the genes encoding the
3 5 functionally linked activities of glycerol dehydratase {dhaB), 1,3-propanediol oxidoreductase (dhaT), glycerol dehydrogenase (dhaD), and dihydroxyacetone kinase (dhaK) are encompassed by the dha regulon. The dha regulon, in Klebsiella pneumoniae and Citrobacter freundii, also encompasses a gene
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encoding a transcriptional activator protein (dhaR). The dha regulons from Citrobacter and Klebsiella have been expressed in Escherichia coli and have been
shown to convert glycerol to 1,3-propanediol.
Neither the chemical nor biological methods described above for the
5 production of 1,3-propanediol are well suited for industrial scale production since the chemical processes are energy intensive and the biological processes are limited to relatively low titer from the expensive starting material, glycerol. These drawbacks could be overcome with a method requiring low energy input and an inexpensive starting material such as carbohydrates or sugars, or by
10 increasing the metabolic efficiency of a glycerol process. Development of either method will require the ability to manipulate the genetic machinery responsible for the conversion of sugars to glycerol and glycerol to 1,3-propanediol.
Biological processes for the preparation of glycerol are known. The overwhelming majority of glycerol producers are yeasts but some bacteria, other
15 fungi and algae are also known. Both bacteria and yeasts produce glycerol by converting glucose or other carbohydrates through the fructose-1,6-bisphosphate pathway in glycolysis or the Embden Meyerhof Parnas pathway, whereas, certain algae convert dissolved carbon dioxide or bicarbonate in the chloroplasts into the 3-carbon intermediates of the Calvin cycle. In a series of steps, the 3-carbon
20 intermediate, phosphoglyceric acid, is converted to glyceraldehyde 3-phosphate which can be readily interconverted to its keto isomer dihydroxyacetone phosphate and ultimately to glycerol.
Specifically, the bacteria Bacillus licheniformis and Lactobacillus lycopersica synthesize glycerol, and glycerol production is found in the
25 halotolerant algae Dunaliella sp. and Asteromonas gracilis for protection against high external salt concentrations. Similarly, various osmotolerant yeasts synthesize glycerol as a protective measure. Most strains of Saccharomyces produce some glycerol during alcoholic fermentation, and this can be increased physiologically by the application of osmotic stress. Earlier this century
30 commercial glycerol production was achieved by the use of Saccharomyces cultures to which "steering reagents" were added such as sulfites or alkalis. Through the formation of an inactive complex, the steering agents block or inhibit the conversion of acetaldehyde to ethanol; thus, excess reducing equivalents (NADH) are available to or "steered" towards DHAP for reduction to produce
35 glycerol. This method is limited by the partial inhibition of yeast growth that is due to the sulfites. This limitation can be partially overcome by the use of alkalis that create" excess NADH equivalents by a different mechanism. In this practice,
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the alkalis initiated a Cannizarro disproportionation to yield ethanol and acetic acid from two equivalents of acetaldehyde.
The gene encoding glycerophosphate dehydrogenase (DARl, QPD1)
has been cloned and sequenced from S. diastaticus (Wang et al., J. Bact. 176,
5 7091-7095 (1994)). The DARl gene was cloned into a shuttle vector and used to transform E. coli where expression produced active enzyme. Wang et al. {supra) recognize that DARl is regulated by the cellular osmotic environment but do not suggest how the gene might be used to enhance 1,3-propanediol production in a recombinant microorganism.
10 Other glycerol-3-phosphate dehydrogenase enzymes have been isolated:
for example, sn-glycerol-3-phosphate dehydrogenase has been cloned and sequenced from Saccharomyces cerevisiae (Larason et al., Mol. Microbiol. 10, 1101 (1993)) and Albertyn et al. (Mo/. Cell. Biol. 14, 4135 (1994)) teach the cloning of GPD1 encoding a glycerol-3-phosphate dehydrogenase from
15 Saccharomyces cerevisiae. Like Wang et al. {supra), both Albertyn et al. and Larason et al. recognize the osmo-sensitivity of the regulation of this gene but do not suggest how the gene might be used in the production of 1,3-propanediol in a recombinant microorganism.
As with G3PDH, glycerol-3-phosphatase has been isolated from
20 Saccharomyces cerevisiae and the protein identified as being encoded by the
GPP1 and GPP2 genes (Norbeck et al., J. Biol. Chem. 271, 13875 (1996)). Like
the genes encoding G3PDH, it appears that GPP2 is osmosensitive.
Although a single microorganism conversion of fermentable carbon source other than glycerol or dihydroxyacetone to 1,3-propanediol is desirable, it has
25 been documented that there are significant difficulties to overcome in such an endeavor. For example, Gottschalk et al. (EP 373 230) teach that the growth of most strains useful for the production of 1,3-propanediol, including Citrobacter freundii, Clostridium autobutylicum, Clostridium butylicum, and Klebsiella pneumoniae, is disturbed by the presence of a hydrogen donor such as fructose or
30 glucose. Strains of Lactobacillus brevis and Lactobacillus buchner, which
produce 1,3-propanediol in co-fermentations of glycerol and fructose or glucose, do not grow when glycerol is provided as the sole carbon source, and, although it has been shown that resting cells can metabolize glucose or fructose, they do not produce 1,3-propanediol (Veiga DA Cunha et al., J. Bacteriol, 174, 1013 (1992)).
35 Similarly, it has been shown that a strain of Ilyobacter polytropus, which produces
1,3-propanediol when glycerol and acetate are provided, will not produce 1,3-propanediol from carbon substrates other than glycerol, including fructose and
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glucose (Steib et al., Arch. Microbiol. 140,139 (1984)). Finally, Tong et al. (AppL Biochem. Biotech. 34, 149 (1992)) taught that recombinant Escherichia coli
transformed with the dha regulon encoding glycerol dehydratase does not produce
1,3-propanediol from either glucose or xylose in the absence of exogenous
5 glycerol.
Attempts to improve the yield of 1,3-propanediol from glycerol have been reported where co-substrates capable of providing reducing equivalents, typically fermentable sugars, are included in the process. Improvements in yield have been claimed for resting cells of Citrobacter freundii and Klebsiella pneumoniae DSM
10 4270 co-fermenting glycerol and glucose (Gottschalk et al., supra.; and Tran-Dinh et al., DE 3734 764); but not for growing cells of Klebsiella pneumoniae ATCC 25955 co-fermenting glycerol and glucose, which produced no 1,3-propanediol (I-T. Tong, Ph.D. Thesis, University of Wisconsin-Madison (1992)). Increased yields have been reported for the cofermentation of glycerol
15 and glucose or fructose by a recombinant Escherichia coli; however, no
1,3-propanediol is produced in the absence of glycerol (Tong et al., supra.). In these systems, single microorganisms use the carbohydrate as a source of generating NADH while providing energy and carbon for cell maintenance or growth. These disclosures suggest that sugars do not enter the carbon stream that
20 produces 1,3-propanediol.
Recently, however, the conversion of carbon substrates, other than glycerol or dihydroxyacetone, to 1,3-propanediol by a single microorganism that expresses a dehydratase enzyme has been described (U.S. 5,686,276; WO 9821339; WO 9928480; and WO 9821341 (US 6013494)). A specific
25 deficiency in the biological processes leading to the production of 1,3-propanediol from either glycerol or glucose has been the low titer of the product achieved via fermentation; thus, an energy-intensive separation process to obtain 1,3-propanediol from the aqueous fermentation broth is required. Fed batch or batch fermentations of glycerol to 1,3-propanediol have led to final titers of 65 g/L
30 by Clostridium butyricum (Saint-Amans et al., Biotechnology Letters 7 (1994)), 71 g/L by Clostridium butyricum mutants (Abbad-Andaloussi et a\.,Appl. Environ. Microbiol. 61,4413 (1995)), 61 g/L by Klebsiella pneumoniae (Homann et al., AppL Bicrobiol. Biotechnol. 33,121 (1990)), and 35 g/L by Citrobacter freundii (Homann et al., supra). Fermentations of glucose to 1,3-propanediol that
3 5 exceed the titer obtained from glycerol fermentations have not yet been disclosed. The problem that remains to be solved is how to biologically produce 1,3-propanediol, with high titer and by a single microorganism, from an
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inexpensive carbon substrate such as glucose or other sugars. The biological production of 1,3-propanediol requires glycerol as a substrate for a two-step
sequential reaction in which a dehydratase enzyme (typically a coenzyme
B12-dependent dehydratase) converts glycerol to an intermediate,
5 3-hydroxypropionaldehyde, which is then reduced to 1,3-propanediol by a
NADH- (or NADPH) dependent oxidoreductase. The complexity of the cofactor requirements necessitates the use of a whole cell catalyst for an industrial process that utilizes this reaction sequence for the production of 1,3-propanediol.
SUMMARY OF THE INVENTION
10 Applicants have solved the stated problem and the present invention
provides for bioconverting a fermentable carbon source directly to 1,3-propanediol at significantly higher titer than previously obtained and with the use of a single microorganism. Glucose is used as a model substrate and E. coli is used as the model host. In one aspect of this invention, recombinant E. coli
15 expressing a group of genes (comprising genes that encode a dehydratase activity, a dehydratase reactivation factor, a 1,3-propanediol oxidoreductase [dhaT), a glycerol-3-phosphate dehydrogenase, and a glycerol-3-phosphatase) convert glucose to 1,3-propanediol at titer that approaches that of glycerol to 1,3-propanediol fermentations.
20 In another aspect of this invention, the elimination of the functional dhaT
gene in this recombinant E. coli results in a significantly higher titer of 1,3-propanediol from glucose. This unexpected increase in titer results in improved economics, and thus, an improved process for the production of 1,3-propanediol from glucose.
25 Furthermore, the present invention may be generally applied to include
any carbon substrate that is readily converted to 1) glycerol, 2) dihydroxyacetone,
3) C3 compounds at the oxidation state of glycerol (e.g., glycerol 3-phosphate), or
4) C3 compounds at the oxidation state of dihydroxyacetone (e.g.,
dihydroxyacetone phosphate or glyceraldehyde 3-phosphate). The production of
30 1,3-propanediol in the dhaT minus strain requires a non-specific catalytic activity that converts 3-HPA to 1,3-propanediol. Identification of the enzyme(s) and/or gene(s) responsible for the non-specific catalytic activity that converts 3-HPA to 1,3-propanediol will lead to production of 1,3-propanediol in a wide range of host microorganisms with substrates from a wide range of carbon-containing
35 substrates. It is also anticipated that the use of this non-specific catalytic activity that converts 3-HPA to 1,3-propanediol will lead to an improved process for the
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production of 1,3-propanediol from glycerol or dihydroxyacetone, by virtue of an improved titer and the resulting improved economics.
This activity has been isolated from E. coli as a nucleic acid fragment
encoding a non-specific catalytic activity for the conversion of 3-
5 hydroxypropionaldehyde to 1,3-propanediol, as set out in SEQ ID NO:58 or as selected from the group consisting of:
(a) an isolated nucleic acid fragment encoding all or a substantial
portion of the amino acid sequence of SEQ ID NO:57;
(b) an isolated nucleic acid fragment that is substantially similar to
10 an isolated nucleic acid fragment encoding all or a substantial
portion of the amino acid sequence of SEQ ID NO:57;
(c) an isolated nucleic acid fragment encoding a polypeptide of at
least 387 amino acids having at least 80% with the amino acid
sequence of SEQ ID NO:57;
15 (d) an isolated nucleic acid fragment that hybridizes with (a) under
hybridization conditions of 0.1X SSC, 0.1% SDS, 65 °C and washed with 2X SSC, 0.1% SDS followed by 0.1X SSC, 0.1% SDS; and
(d) an isolated nucleic acid fragment that is complementary to (a),
20 (b), (c), or (d). Alternatively, the nonspecific catalytic acitivity
is embodieed in the polypeptide as set out in SEQ ID NO:57. A chimeric gene may be constructed comprising the isolated nucleic acid fragment described above operably linked to suitable regulatory sequences. This chimeric gene can be used to transform miciroorganisms selected from the group
25 consisting of Citrobacter, Enterobacter, Clostridium, Klebsiella, Aerobacter, Lactobacillus, Aspergillus, Saccharomyces, Schizosaccharomyces, Zygosaccharomyces, Pichia, Kluyveromyces, Candida, Hansenula, Debaryomyces, Mucor, Torulopsis, Methylobacter, Salmonella, Bacillus, Aerobacter, Streptomyces, Escherichia, and Pseudomonas. E. coli is the
30 preferred host.
Accordingly, the present invention provides a recombinant microorganism, useful for the production of 1,3-propanediol comprising: (a) at least one gene encoding a polypeptide having glycerol-3-phosphate dehydrogenase activity; (b) at least one gene encoding a polypeptide having glycerol-3-phosphatase
3 5 activity; (c) at least one gene encoding a polypeptide having a dehydratase
activity; (d) at least one gene encoding a dehydratase reactivation factor, (e) at least one endogenous gene encoding an non-specific catalytic activity sufficient to
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convert 3-hydroxypropionaldehyde to 1,3-propanediol, wherein no functional dhaT gene encoding a 1,3-propanediol oxidoreductase is present. The preferred
embodiment is a recombinant microorganism (preferably E. coli) where no dhaT
gene is present. Optionally, the recombinant microorganism may comprise
5 mutations (e.g., deletion mutations or point mutations) in endogenous genes selected from the group consisting of: (a) a gene encoding a polypeptide having glycerol kinase activity; (b) a gene encoding a polypeptide having glycerol dehydrogenase activity; and (c) gene encoding a polypeptide having triosephosphate isomerase activity.
10 In another embodiment the invention includes a process for the production
of 1,3-propanediol comprising:(a) contacting, under suitable conditions, a recombinant E. coli comprising a dha regulon and lacking a functional dhaT gene encoding a 1,3-propanediol oxidoreductase activity with at least one carbon source, wherein the carbon source is selected from the group consisting of
15 monosaccharides, oligosaccharides, polysaccharides, and single-carbon substrates; and (b) optionally recovering the 1,3-propanediol produced in (a). The invention also provides a process for the production of 1,3-propanediol from a recombinant microorganism comprising: (a) contacting the recombinant microorganism of the present invention with at least one carbon
20 source selected from the group consistmg of monosaccharides, oligosaccharides, polysaccharides, and single-carbon substrates whereby 1,3-propanediol is produced; and (b) optionally recovering the 1,3-propanediol produced in (a).
Similarly the invention intends to provide a process for the production of 1,3-propanediol from a recombinant microorganism comprising:
25 (a) contacting a recombinant microorganism with at least one carbon
source, said recombinant microorganism comprising:
(i) at least one gene encoding a polypeptide having a dehydratase
activity;
(ii) at least one gene encoding a dehydratase reactivation factor;
30 (iii) at least one endogenous gene encoding a non-specific catalytic
activity sufficient to convert 3-hydroxypropionaldehyde to 1,3-propanediol; wherein no functional dhaT gene encoding a 1,3-propanediol oxidoreductase is present;
said carbon source selected from the group consisting of glycerol and
35 dihydroxyacetone, wherein 1,3-propanediol is produced and;
(b) optionally recovering the 1,3-propanediol produced in (a).
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Yet another aspect of the invention provides for the co-feeding of the carbon substrate. In this embodiment for the production of 1,3-propanediol, the
steps are: (a) contacting a recombinant E. coli with a first source of carbon and
with a second source of carbon, said recombinant E. coli comprising: (i) at least
5 one exogenous gene encoding a polypeptide having a dehydratase activity; (ii) at least one exogenous gene encoding a dehydratase reactivation factor; (iii) at least one exogenous gene encoding a non-specific catalytic activity sufficient to convert 3-hydroxypropionaldehyde to 1,3-propanediol, wherein no functional dhaTgene encoding a 1,3-propanediol oxidoreductase activity is present in the recombinant
10 E. coli and wherein said first carbon source is selected from the group consisting of glycerol and dihydroxyacetone, and said second carbon source is selected from the group consisting of monosaccharides, oligosaccharides, polysaccharides, and single-carbon substrates, and (b) the 1,3-propanediol produced in (a) is optionally recovered. The co-feed may be sequential or simultaneous. The recombinant
15 E. coli used in a co-feeding embodiemtn may further comprise: (a) a set of
exogenous genes consisting of (i) at least one gene encoding a polypeptide having glycerol-3-phosphate dehydrogenase activity; (ii) at least one gene encoding a polypeptide having glycerol-3-phosphatase activity; and (iii) at least one subset of genes encoding the gene products of dhaR, orfY, or/X, orJW, dhaBl, dhaB2,
20 dhaB3 and orfZ, and (b) a set of endogenous genes, each gene having a mutation inactivating the gene, the set consisting of: (i) a gene encoding a polypeptide having glycerol kinase activity; (ii) a gene encoding a polypeptide having glycerol dehydrogenase activity; and (iii) a gene encoding a polypeptide having triosephosphate isomerase activity.
25 Useful recombinant E. coli strains include recombinant E. coli strain
KLP23 comprising: (a) a set of two endogenous genes, each gene having a mutation inactivating the gene, the set consisting of: (i) a gene encoding a polypeptide having a glycerol kinase activity; and (ii) a gene encoding a polypeptide having a glycerol dehydrogenase activity; (b) at least one exogenous
30 gene encoding a polypeptide having glycerol-3-phosphate dehydrogenase activity; (c) at least one exogenous gene encoding a polypeptide having glycerol73-phosphatase activity; and (d) a plasmid pKP32 and a recombinant E. coli strain RJ8 comprising: (a) set of three endogenous genes, each gene having a mutation inactivating the gene, the set consisting of: (i) a gene encoding a polypeptide
35 having a glycerol kinase activity; (ii) a gene encoding a polypeptide having a
glycerol dehydrogenase activity; and (iii) a gene encoding a polypeptide having a triosephosphate isomerase activity.
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Other useful embodiments include recombinant E. coli comprising: (a) a set of exogenous genes consisting of: (i) at least one gene encoding a polypeptide having a dehydratase activity; (ii) at least one gene encoding a polypeptide having
glycerol-3-phosphate dehydrogenase activity; (iii) at least one gene encoding a
5 polypeptide having glycerol-3-phosphatase activity; and (iv) at least one gene encoding a dehydratase reactivation factor; and (b) at least one endogenous gene encoding a non-specific catalytic activity to convert 3-hydroxypropionaldehyde to 1,3-propanediol; wherein no functional dhaT gene encoding a 1,3-propanediol oxidoreductase activity is present in the recombinant E. coli.
10 Another embodiemtn is a recombinant E. coli comprising: (a) a set of
exogenous genes consisting of (i) at least one gene encoding a polypeptide having glycerol-3-phosphate dehydrogenase activity; (ii) at least one gene encoding a polypeptide having glycerol-3-phosphatase activity; and (iii) at least one subset of genes encoding the gene products of dhaR, orfY, orjX, orJW, dhaBl, dhaB2,
15 dhaB3 and orfZ, and (b) at least one endogenous gene encoding a non-specific catalytic activity to convert 3-hydroxypropionaldehyde to 1,3-propanediol, wherein no functional dhaT gene encoding a 1,3-propanediol oxidoreductase
activity is present in the recombinant E. coli. This embodiment also includes a
process using a recombinant E. coli further comprising a set of endogenous
20 genes, each gene having a mutation inactivating the gene, the set consisting of: (a) a gene encoding a polypeptide having glycerol kinase activity; (b) a gene encoding a polypeptide having glycerol dehydrogenase activity; and (c) a gene encoding a polypeptide having triosephosphate isomerase activity.
This embodiment still further includes a process for the bioproduction of
25 1,3-propanediol comprising: (a) contacting under suitable conditions the immediately disclosed recombinant E. coli with at least one carbon source selected from the group consisting of monosaccharides, oligosaccharides, polysaccharides, and single-carbon substrates whereby 1,3-propanediol is produced; and (b) optionally recovering the 1,3-propanediol produced in (a).
30 And also includes a further process for the bioproduction of
1,3-propanediol comprising: (a) contacting the recombinant E. coli of the immediately disclosed embodiments that further comprise: (i) at least one exogenous gene encoding a polypeptide having a dehydratase activity; (ii) at least one exogenous gene encoding a dehydratase reactivation factor; (iii) at least one
35 endogenous gene encoding a non-specific catalytic activity to convert 3-hydroxypropionaldehyde to 1,3-propanediol, with at least one carbon source selected from
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the group consisting of glycerol and dihydroxyacetone, and (b) optionally recovering the 1,3-propanediol produced in (a).
BRIEF DESCRIPTION OF THE DRAWINGS.
SEQUENCE DESCRIPTIONS, AND BIOLOGICAL DEPOSITS
5 The invention can be more fully understood from the following detailed
description, Figures, the accompanying sequence descriptions, and biological deposits that form parts of this application.
Figure 1 presents the gene organization within the sequence of the dha regulon subclone pHK28-26.
10 Figure 2 presents a graph of the extracellular soluble protein (g/L)
compared between two fermentations runs essentially as described in Example 7 using a constant feed of vitamin B^. In one case, solid lines, the strain used was KLP23/pAH48/pKP32. In the other case, dashed lines, the strain used was KLP23/pAH48/pDT29.
15 Figure 3 presents a graph of the cell viability [(viable cells/mL)/OD550]
compared between two fermentations runs essentially as described in Example 7 using a constant feed of vitamin B12. In one case (solid lines), the strain used was KLP23/pAH48/pKP32. In the other case (dashed lines), the strain used was KLP23/pAH48/pDT29.
20 Figure 4 presents a graph of the yield of glycerol from glucose compared
between two fermentations runs essentially as described in Example 7, but in the absence of vitamin B!2 or coenzyme B12. In one case (solid lines), the strain used was KLP23/pAH48/pKP32. In the other case (dashed lines), the strain used was KLP23/pAH48/pDT29.
25 Figure 5 is a flow diagram illustrating the metabolic conversion of glucose
to 1,3-propanediol.
Figure 6 is a 2D-PAGE membrane blot with the soluble protein fraction extracted from a band showing endogenous E. coli oxidoreductase activity (non-specific catalytic activity) on a native gel.
30 The 68 sequence descriptions and the sequence listing attached hereto will
comply with the rules governing nucleotide and/or amino acid sequence disclosures in patent applications as set forth in 37 C.F.R. §1.821-1.825 ("Requirements for Patent Applications Containing Nucleotide Sequences and/or
Amino Acid Sequence Disclosures - the Sequence Rules") and will be consistent
35 with World Intellectual Property Organization (WIPO) Standard ST2.5 (1998) and the sequence listing requirements of the EPO and PCT (Rules 5.2 and 49.5(a-bis), and Section 208 and Annex C of the Administration Instructions). The Sequence
11

10

Descriptions contain the one letter code for nucleotide sequence characters and the
three letter codes for amino acids as defined in conformity with the IUPAC-IYUB standards described in Nucleic Acids Res. 13, 3021-3030 (1985) and in the BiochemicalJournal 219, 345-373 (1984) which are herein incorporated by reference.
SEQ ID NO:l contains the nucleotide sequence determined from a 12.1 kb EcoRI-Sall fragment from pKPl (cosmid containing DNA from Klebsiella pneumoniae), subcloned into pIBI31 (IBI Biosystem, New Haven, CT), and termed pHK28-26. Table 1 further details genes, corresponding base pairs identified within SEQ ID NO: 1, and associated functionality. See also Example 1.

-SEQ ID NO:57 contains the amino acid sequence determined for YqhD
SEQ ID NO:58 contains the nucleotide sequence determined for yqhD
Applicants have made the following biological under the terms of the Budapest Treaty on the International Recognition of the Deposit of Micro-organisms for the Purposes of Patent Procedure:-

20
23

Depositor Identification
Reference
Transformed E. coli DH5cc containing a portion of the Klebsiella genome encoding the glycerol dehydratase enzyme
transformed E. coli DH5α containing cosmit pKP4 containing a portion of Klebsiella genome encoding a diol dehydratase enzyme
E. coli MSP33.6


Date of Deposit
Int'l Depository Designation
ATCC 69789 , 18 April 1995
ATCC 69790 18 April 1995
ATCC 98598 25 November 1997



) glpK mutant E. coli RJF1 0m

ATCC 98597 25 November 1997



35
40

The deposit(s) will be maintained in the indicated international depository for at least 30 years and will be made available to the public upon the grant of a patent disclosing it. The availability of a deposit does not constitute a license to practice the subject invention in derogation of patent rights granted by government action.
As used herein, "ATCC" refers to the American Type Culture Collection international depository located 10801 University Blvd., Manassas, VA 20110-2209 U.S.A. The "ATCC No." is the accession number to cultures on deposit with the ATCC



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DETAILED DESCRIPTION OF THE INVENTION
The present invention provides for an improved process for bioconverting
a fermentable carbon source directly to 1,3-propanediol using a single
microorganism. The method is characterized by improved titer, yield, and cell
5 viability as well as a decrease in cell lysis during fermentation.
The present invention is based, in part, upon the observation that 1,3-propanediol fermentation processes comprising 1,3-propanediol oxidoreductase (dhaT) are characterized by high levels of 3HPA and other aldehydes and ketones in the medium, which is correlated to a decrease in cell
10 viability. The present invention is also based, in part, upon the unexpected finding that the model host, E. coli, is capable of converting 3-HPA to 1,3-propanediol by an endogenous non-specific catalytic activity capable of converting 3-hydroxypropionaldehyde to 1,3-propanediol. The present invention is further based, in part, upon the unexpected finding that an E. coli fermentation
15 process comprising this non-specific catalytic activity and lacking a functional
dhaT results in increased cell viability during fermentation and provides for higher titers and/or yields of 1,3-propanediol than a fermentation process comprising a functional dhaT.
In one aspect, glycerol is a model substrate, the host microorganism has a
20 mutation in wild-type dhaT such that there is no 1,3-propanediol oxidoreductase activity and comprises a non-specific catalytic activity sufficient to convert 3-hydroxypropionaldehyde to 1,3-propanediol. In another aspect, glucose is a model substrate and recombinant E. coli is a model host. In this aspect, E. coli comprises an endogenous non-specific catalytic activity sufficient to convert
25 3-hydroxypropionaldehyde to 1,3-propanediol. In one embodiment, the nonspecific catalytic activity is an alcohol dehydrogenase.
In one aspect, the present invention provides a recombinant E. coli expressing a group of genes comprising (a) at least one gene encoding a polypeptide having glycerol-3-phosphate dehydrogenase activity; (b) at least one
30 gene encoding a polypeptide having glycerol-3-phosphatase activity; (c) at least one gene encoding a polypeptide having a dehydratase activity; (d) at least one gene encoding a dehydratase reactivation factor; and (e) at least one endogenous gene encoding an non-specific catalytic activity sufficient to convert 3-hydroxypropionaldehyde to 1,3-propanediol; use of this microorganism converts glucose
35 to 1,3-propanediol at a high titer. In another aspect of this invention, the
elimination of the functional dhaT gene in this recombinant E. coli provides an
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unexpectedly higher titer of 1,3-propanediol from glucose than previously attained.
The present invention provides an improved method for the biological production of 1,3-propanediol from a fermentable carbon source in a single
5 microorganism. In one aspect of the present invention, an improved process for the conversion of glucose to 1,3-propanediol is achieved by the use of a recombinant microorganism comprising a host E. coli transformed with the Klebsiella pneumoniae dha regulon genes dhaR, or/Y, dhaT, orfX, orfW, dhaBl, dhaB2, dhaB3, and orfZ, all these genes arranged in the same genetic organization
10 as found in wild type Klebsiella pneumoniae. The titer obtained for the
fermentation process is significantly higher than any titer previously reported for a similar fermentation. This improvement relies on the use of the plasmid pDT29 as described in Example 6 and Example 7.
In another aspect of the present invention, a further improved process for
15 the production of 1,3-propanediol from glucose is achieved using a recombinant E. coli containing genes encoding a G3PDH, a G3P phosphtase, a dehydratase, and a dehydratase reactivation factor compared to a process using a recombinant E. coli containing genes encoding a G3PDH, a G3P phosphatase, a dehydratase, a dehydratase reactivation factor, and also a functional dhaT. The dramatically
20 improved process relies on an endogenous gene encoding a non-specific catalytic activity, expected to be an alcohol dehydrogenase, which is present in E. coli. The dramatic improvement in the process is evident as an increase in
1,3-propanediol titer as illustrated in Examples 7 and 9. The improvement in the process is also evident as a decrease in cell lysis as determined by the extracellular
25 soluble protein concentration in the fermentation broth. This aspect of the
invention is illustrated in Figure 2. Additionally, the improvement in the process is evident as prolonged cell viability over the course of the fermentation. This aspect of the invention is illustrated in Figure 3. Furthermore, the improvement in the process is also evident as an increase in yield. In E. coli expressing a
30 1,3-propanediol oxidoreductase (dhaT) (for example, E. coli KLP23 transformed with the plasmid pDT29), glycerol can be metabolized to a product other than 3-HPA. In direct contrast, in E. coli not expressing a 1,3-propanediol oxidoreductase (dhaT) (for example, E. coli KLP23 transformed with the plasmid pKP32), glycerol is not metabolized to a product other than 3-HPA. That this
3 5 cryptic pathway is attributable to the presence or absence of a functional dhaT is demonstrated by the lower yield of glycerol from glucose as illustrated in Figure 4.
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As used herein the following terms may be used for interpretation of the claims and specification.
The terms "glycerol-3-phosphate dehydrogenase" and "G3PDH" refer to a
polypeptide responsible for an enzyme activity that catalyzes the conversion of
5 dihydroxyacetone phosphate (DHAP) to glycerol-3-phosphate (G3P). In vivo G3PDH may be NADH; NADPH; or FAD-dependent. When specifically referring to a cofactor specific glycerol-3-phosphate dehydrogenase, the terms "NADH-dependent glycerol-3-phosphate dehydrogenase", "NADPH-dependent glycerol-3-phosphate dehydrogenase" and "FAD-dependent glycerol-3-phosphate
10 dehydrogenase" will be used. As it is generally the case that NADH-dependent and NADPH-dependent glycerol-3-phosphate dehydrogenases are able to use NADH and NADPH interchangeably (for example by the gene encoded by gpsA), the terms NADH-dependent and NADPH-dependent glycerol-3-phosphate dehydrogenase will be used interchangeably. The NADH-dependent enzyme
15 (EC 1.1.1.8) is encoded, for example, by several genes including GPDl (GenBank Z74071x2), or GPD2 (GenBank Z35169xl), or GPD3 (GenBank G984182), or DAR1 (GenBank Z74071 x2). The NADPH-dependent enzyme (EC 1.1.1.94) is encoded by gpsA (GenBank U321643, (cds 197911-196892) G466746 and L45246). The FAD-dependent enzyme (EC 1.1.99.5) is encoded by GUT2
20 (GenBank Z47047x23), or glpD (GenBank G147838), or glpABC (GenBank
M20938) (see WO 9928480 and references therein, which are herein incorporated by reference).
The terms "glycerol-3-phosphatase", "sn-glycerol-3-phosphatase", or "d,l-glycerol phosphatase", and "G3P phosphatase" refer to a polypeptide
25 responsible for an enzyme activity that catalyzes the conversion of glycerol-3-phosphate and water to glycerol and inorganic phosphate. G3P phosphatase is encoded, for example, by GPP1 (GenBank Z47047xl25), or GPP2 (GenBank Ul 8813x11) (see WO 9928480 and references therein, which are herein incorporated by reference).
30 The term "glycerol kinase" refers to a polypeptide responsible for an
enzyme activity that catalyzes the conversion of glycerol and ATP to glycerol-3-phosphate and ADP. The high-energy phosphate donor ATP may be replaced by physiological substitutes (e.g., phosphoenolpyruvate). Glycerol kinase is encoded, for example, by GUT1 (GenBank Ul 1583x19) and glpK (GenBank
35 L19201) (see WO 9928480 and references therein, which are herein incorporated by reference).
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The term "glycerol dehydrogenase" refers to a polypeptide responsible for an enzyme activity that catalyzes the conversion of glycerol to dihydroxyacetone (EC. 1.1.1.6) or glycerol to glyceraldehyde (E.C. 1.1.1.72). A polypeptide
responsible for an enzyme activity that catalyzes the conversion of glycerol to
5 dihydroxyacetone is also referred to as a "dihydroxyacetone reductase". Glycerol
dehydrogenase may be dependent uponNADH (E.C. 1.1.1.6), NADPH
(E.C. 1.1.1.72), or other cofactors (e.g., E.C. 1.1.99.22). A NADH-dependent
glycerol dehydrogenase is encoded, for example, by gldA (GenBank U00006) (see
WO 9928480 and references therein, which are herein incorporated by reference).
10 The term "dehydratase enzyme" or "dehydratase" will refer to any enzyme
activity that catalyzes the conversion of a glycerol molecule to the product 3-hydroxypropionaldehyde. For the purposes of the present invention the dehydratase enzymes include a glycerol dehydratase (E.C. 4.2.1.30) and a diol
dehydratase (E.C. 4.2.1.28) having preferred substrates of glycerol and
15 1,2-propanediol, respectively. Genes for dehydratase enzymes have been identified in Klebsiella pneumoniae, Citrobacter freundii, Clostridium pasteurianum, Salmonella typhimurium, and Klebsiella oxytoca^ In each case, the dehydratase is composed of three subunits: the large or "a" subunit, the medium or "B" subunit, and the small or "β" subunit. Due to the wide variation in gene
20 nomenclature used in the literature, a comparative chart is given in Table 1 to
facilitate identification. The genes are also described in, for example, Daniel et al. (FEMS Microbiol. Rev. 22, 553 (1999)) and Toraya and Mori (J. Biol. Chem. 274, 3372 (1999)). Referring to Table 1, genes encoding the large or "a" subunit of glycerol dehydratase include dhaBl, gldA and dhaB; genes encoding the medium
25 or "β" subunit include dhaB2, gldB, and dhaC; genes encoding the small or "y" subunit include dhaB3, gldC, and dhaE. Also referring to Table 1, genes encoding the large or "α" subunit of diol dehydratase include pduC and pddA; genes encoding the medium or "β" subunit include pduD and pddB; genes encoding the small or "y" subunit include pduE and pddC.






16

Table 1: Comparative chart of gene names and GenBank references for dehydratase and GENE FUNCTION: dehydratase linked functions.
regulatory unknown reactivation 1,3-PD dehydrogenase unknown
gene base pairs gene base pairs geme base pairs gene base pairs gene base pairs
ORGANISM (GenBank Reference)
AC pneumoniae (SEQ ID NO.l) dhaR 2209-4134 or/W 4112-4642 orJX 4643-4996 dhaT 5017-6108 orfY 6202-6630
K. pneumoniae (U30903) orflc 7116-7646 orfib 6762-7115 dhaT 5578-6741 orJ2a 5125-5556
K. pneumoniae (U60992) gdrB
C.)hjwK/H(U09771) dhaR 3746-5671 or/W 5649-6179 orJX 6180-6533 dhaT 6550-7713 orJY 7736-8164
C. pasteurianum (AF051373)
O pasteurianum (AF006034) or/W 210-731 orJX 1-196 dhaT 1232-2389 orfY 746-1177
S: typhimurium (AF026270) pduH 8274-8645
Koxytoca (AFO17781) ddrB 2063-2440
K. oxytoco {AF051313)
| * GENE FUNCTION:
dehydratase, a dehydr atase, (i dehydratase, y reactivation
! gene base pairs iRene base pairs gene base Dairs gene base pairs
ORGANISM (GenBank Reference)
K, pneumoniae (SEQ ID NO:l) dhaBl 7044-8711 dhaBl 8724-9308 dhaBl 9311-9736 or/Z 9749-11572
K. pneumoniae (U3O903) dhaBl 3047-4714 dhaBl 2450-2890 dhaBl 2022-2447 dhaB4 186-2009
K. pneumoniae (U60992) gldA 121-1788 : gldB 1801-2385 gldC 2388-2813 gdrA
C.freundiiQJ09n\) dhaB 8556-10223 dhaC 10235-10819 dhaE 10822-11250 or/Z 11261-13072
C. pasteurianum (AF051373) dhaB 84-1748 IdhaC 1779-2318 dhaE 2333-2773 orfZ 2790-4598
C. pasteurianum (AF006034)
S. typhimurium (AF026270) pduC 3557-5221 pduD 5232-5906 pduE 5921-6442 pduG 6452-8284
K. oxytoca (AF017781) ddrA 241-2073
K. OJtyroco(AF051373) pddi 121-1785 pddB 1796-2470 pddC 2485-3006

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Glycerol and diol dehydratases are subject to mechanism-based suicide inactivation by glycerol and some other substrates (Daniel et al., FEMS Microbiol. Rev. 22,553 (1999)). The terra "dehydratase reactivation factor" refers to those
proteins responsible for reactivating the dehydratase activity. The terms
5 "dehydratase reactivating activity", "reactivating the dehydratase activity" or "regenerating the dehydratase activity" refers to the phenomenon of converting a dehydratase not capable of catalysis of a substrate to one capable of catalysis of a substrate or to the phenomenon of inhibiting the inactivation of a dehydratase or the phenomenon of extending the useful half-life of the dehydratase enzyme in
10 vivo. Two proteins have been identified as being involved as the dehydratase
reactivation factor (see WO 9821341 (US 6013494) and references therein, which are herein incorporated by reference; Daniel et al., supra; Toraya and Mori, J. Biol. Chem. 274, 3372 (1999); and Tobimatsu et al., J. Bacteriol. 181,4110 (1999)). Referring to Table 1, genes encoding one of the proteins include orfZ,
15 dhaB4, gdrA,pduG and ddrA. Also referring to Table 1, genes encoding the second of the two proteins include orfX, orflb, gdrB,pduH and ddrB. The terms "1,3-propanediol oxidoreductase", "1,3-propanediol dehydrogenase" or "DhaT" refer to the polypeptide(s) responsible for an enzyme activity that is capable of catalyzing the interconversion of 3-HPA and
20 1,3-propanediol provided the gene(s) encoding such activity is found to be
physically or transcriptionally linked to a dehydratase enzyme in its natural (i.e., wild type) setting; for example, the gene is found within a dha regulon as is the case with dhaT&om Klebsiella pneumonia. Referring to Table 1, genes encoding a 1,3-propanediol oxidoreductase include dhaT from Klebsiella pneumoniae,
25 Citrobacterfreundii, and Clostridium pasteurianum. Each of these genes encode a polypeptide belonging to the family of type III alcohol dehydrogenases, exhibits a conserved iron-binding motif, and has a preference for the NAD+/NADH linked intercoversion of 3-HPA and 1,3-propanediol (Johnson and Lin, J. Bacteriol. 169, 2050 (1987); Daniel et al., J. Bacteriol 177, 2151 (1995); and Leurs et al., FEMS
30 Microbiol. Lett. 154, 337 (1997)). Enzymes with similar physical properties have been isolated from Lactobacillus brevis and Lactobacillus buchneri (Veiga da Dunha and Foster, Appl. Environ. Microbiol. 58, 2005 (1992)).
The term "dha regulon" refers to a set of associated genes or open reading frames encoding various biological activities, including but not limited to a
3 5 dehydratase activity, a reactivation activity, and a 1,3-propanediol oxidoreductase. Typically a dha regulon comprises the open reading frames dhaR, orjY, dhaT, orfX, orjW, dhaBl, dhaB2, dhaB3, and or/Z as described herein.
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The term "non-specific catalytic activity" refers to the polypeptide(s) responsible for an enzyme activity that is sufficient to catalyze the interconversion
of 3-HPA and 1,3 -propanediol and specifically excludes 1,3-propanediol oxidoreductase(s). Typically these enzymes are alcohol dehydrogenases. Such
5 enzymes may utilize cofactors other than NAD+/NADH, including but not limited to flavins such as FAD or FMN. A gene(s) for a non-specific alcohol dehydrogenase(s) is found, for example, to be endogenously encoded and functionally expressed within the microorganism E. coli KLP23.
The terms "function" or "enzyme function" refer to the catalytic activity of
10 an enzyme in altering the energy required to perform a specific chemical reaction. It is understood that such an activity may apply to a reaction in equilibrium where the production of either product or substrate may be accomplished under suitable conditions.
The terms "polypeptide" and "protein" are used interchangeably.
15 The terms "carbon substrate" and "carbon source" refer to a carbon source
capable of being metabolized by host microorganisms of the present invention and particularly carbon sources selected from the group consisting of monosaccharides, oligosaccharides, polysaccharides, and one-carbon substrates or mixtures thereof.
20 The terms "host cell" or "host microorganism" refer to a microorganism
capable of receiving foreign or heterologous genes and of expressing those genes to produce an active gene product.
The terms "foreign gene", "foreign DNA", "heterologous gene" and "heterologous DNA" refer to genetic material native to one organism that has
25 been placed within a host microorganism by various means. The gene of interest may be a naturally occurring gene, a mutated gene, or a synthetic gene.
The terms "transformation" and "transfection" refer to the acquisition of new genes in a cell after the incorporation of nucleic acid. The acquired genes may be integrated into chromosomal DNA or introduced as extrachromosomal
30 replicating sequences. The term "transformant" refers to the product of a transformation.
The term "genetically altered" refers to the process of changing hereditary material by transformation or mutation.
The terms "recombinant microorganism" and "transformed host" refer to
35 any microorganism having been transformed with heterologous or foreign genes or extra copies of homologous genes. The recombinant microorganisms of the present invention express foreign genes encoding glycerol-3-phosphate
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dehydrogenase (GPD1), glycerol-3-phosphatase (GPP2), glycerol dehydratase (dhaBl, dhaB2 anddhaB3), dehydratase reactivation factor (orfZ and orfiC), and
optionally 1 ,3-propanediol oxidoreductase (dhaT) for the production of
1,3-propanediol from suitable carbon substrates. A preferred embodiment is an
5 E. coli transformed with these genes but lacking a functional dhaT. A host
microorganism, other than E. coli, may also be transformed to contain the
disclosed genes and the gene for the non-specific catalytic activity for the
interconversion of 3-HPA and 1,3-propanediol, specifically excluding 1,3-
propanediol oxidoreductase(s) (dhaT).
10 "Gene" refers to a nucleic acid fragment that expresses a specific protein,
including regulatory sequences preceding (5' non-coding) and following (3' non-coding) the coding region. The terms "native" and "wild-type" refer to a gene as found in nature with its own regulatory sequences.
The terms "encoding" and "coding" refer to the process by which a gene,
15 through the mechanisms of transcription and translation, produces an amino acid sequence. It is understood that the process of encoding a specific amino acid sequence includes DNA sequences that may involve base changes that do not cause a change in the encoded amino acid, or which involve base changes which may alter one or more amino acids, but do not affect the functional properties of
20 the protein encoded by the DNA sequence. It is therefore understood that the invention encompasses more than the specific exemplary sequences.
The term "isolated" refers to a protein or DNA sequence that is removed from at least one component with which it is naturally associated.
An "isolated nucleic acid molecule" is a polymer of RNA or DNA that is
25 single- or double-stranded, optionally containing synthetic, non-natural or altered nucleotide bases. An isolated nucleic acid molecule in the form of a polymer of DNA may be comprised of one or more segments of cDNA, genomic DNA or synthetic DNA.
"Substantially similar" refers to nucleic acid molecules wherein changes in
30 one or more nucleotide bases result in substitution of one or more amino acids, but do not affect the functional properties of the protein encoded by the DNA sequence. "Substantially similar" also refers to nucleic acid molecules wherein changes in one or more nucleotide bases do not affect the ability of the nucleic acid molecule to mediate alteration of gene expression by antisense or
3 5 co-suppression technology. "Substantially similar" also refers to modifications of
the nucleic acid molecules of the instant invention (such as deletion or insertion of one or more nucleotide bases) that do not substantially affect the functional
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properties of the resulting transcript vis-a-vis the ability to mediate alteration of gene expression by antisense or co-suppression technology or alteration of the
functional properties of the resulting protein molecule. The invention
encompasses more than the specific exemplary sequences.
5 For example, it is well known in the art that alterations in a gene which
result in the production of a chemically equivalent amino acid at a given site, but
do not effect the functional properties of the encoded protein are common. For the
purposes of the present invention substitutions are defined as exchanges within
one of the following five groups:
10 1. Small aliphatic, nonpolar or slightly polar residues: Ala, Ser, Thr
(Pro,Gly);
2. Polar, negatively charged residues and their amides: Asp, Asn,
Glu, Gin;
3. Polar, positively charged residues: His, Arg, Lys;
15 4. Large aliphatic, nonpolar residues: Met, Leu, lie, Val (Cys); and
5. Large aromatic residues: Phe, Tyr,Trp. Thus, a codon for the amino acid alanine, a hydrophobic amino acid, may be substituted by a codon encoding another less hydrophobic residue (such as glycine) or a more hydrophobic residue (such as valine, leucine, or isoleucine).
20 Similarly, changes which result in substitution of one negatively charged residue for another (such as aspartic acid for glutamic acid) or one positively charged residue for another (such as lysine for arginine) can also be expected to produce a functionally equivalent product.
In many cases, nucleotide changes which result in alteration of the
25 N-terminal and C-terminal portions of the protein molecule would also not be expected to alter the activity of the protein.
Each of the proposed modifications is well within the routine skill in the art, as is determination of retention of biological activity of the encoded products. Moreover, the skilled artisan recognizes that substantially similar sequences
30 encompassed by this invention are also defined by their ability to hybridize, under stringent conditions (0.1X SSC, 0.1% SDS, 65 °C and washed with 2X SSC, 0.1% SDS followed by 0.1 X SSC, 0.1% SDS), with the sequences exemplified herein. Preferred substantially similar nucleic acid fragments of the instant invention are those nucleic acid fragments whose DNA sequences are at least 80% identical to
35 the DNA sequence of the nucleic acid fragments reported herein. More preferred nucleic acid fragments are at least 90% identical to the DNA sequence of the nucleic acid fragments reported herein. Most preferred are nucleic acid fragments
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that are at least 95% identical to the DNA sequence of the nucleic acid fragments reported herein.
A nucleic acid fragment is "hybridizable" to another nucleic acid fragment,
such as a cDNA, genomic DNA, or RNA, when a single stranded form of the
5 nucleic acid fragment can anneal to the other nucleic acid fragment under the appropriate conditions of temperature and solution ionic strength. Hybridization and washing conditions are well known and exemplified in Sambrook, J., Fritsch, E. F. and Maniatis, T. Molecular Cloning: A Laboratory Manual. Second Edition, Cold Spring Harbor Laboratory Press, Cold Spring Harbor (1989), particularly
10 Chapter 11 and Table 11.1 therein (entirely incorporated herein by reference).
The conditions of temperature and ionic strength determine the "stringency" of the hybridization. For preliminary screening for homologous nucleic acids, low stringency hybridization conditions, corresponding to a Tm of 55 °, can be used, e.g., 5X SSC, 0.1% SDS, 0.25% milk, and no formamide; or 30% formamide, 5X
15 SSC, 0.5% SDS. Moderate stringency hybridization conditions correspond to a higher Tm, e.g., 40% formamidet with 5X or 6X SSC. Hybridization requires that the two nucleic acids contain complementary sequences, although depending on the stringency of the hybridization, mismatches between bases are possible. The appropriate stringency for hybridizing nucleic acids depends on the length of the
20 nucleic acids and the degree of complementation, variables well known in the art. The greater the degree of similarity or homology between two nucleotide sequences, the greater the value of Tm for hybrids of nucleic acids having those sequences. The relative stability (corresponding to higher Tm) of nucleic acid
hybridization decreases in the following order: RNA-.RNA, DNA:RNA,
25 DNA:DNA. For hybrids of greater than 100 nucleotides in length, equations for calculating Tm have been derived (see Sambrook et al., supra, 9.50-9.51). For hybridization with shorter nucleic acids, i.e., oligonucleotides, the position of mismatches becomes more important, and the length of the oligonucleotide determines its specificity (see Sambrook et al., supra, 11.7-11.8). In one
30 embodiment the length for a hybridizable nucleic acid is at least about 10
nucleotides. Preferable a minimum length for a hybridizable nucleic acid is at least about 15 nucleotides; more preferably at least about 20 nucleotides; and most preferably the length is at least 30 nucleotides. Furthermore, the skilled artisan
will recognize that the temperature and wash solution salt concentration may be
35 adjusted as necessary according to factors such as length of the probe.
A "substantial portion" refers to an amino acid or nucleotide sequence
which comprises enough of the amino acid sequence of a polypeptide or the
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nucleotide sequence of a gene to afford putative identification of that polypeptide or gene, either by manual evaluation of the sequence by one skilled in the art, or
by computer-automated sequence comparison and identification using algorithms
such as BLAST (Basic Local Alignment Search Tool; Altschul et al., J. Mol.Biol.
5 215:403-410 (1993); see also www.ncbi.nlm.nih.gov/BLAST/). In general, a sequence often or more contiguous amino acids or thirty or more nucleotides is necessary in order to putatively identify a polypeptide or nucleic acid sequence as homologous to a known protein or gene. Moreover, with respect to nucleotide sequences, gene-specific oligonucleotide probes comprising 20-30 contiguous
10 nucleotides may be used in sequence-dependent methods of gene identification (e.g., Southern hybridization) and isolation (e.g., in situ hybridization of bacterial colonies or bacteriophage plaques). In addition, short oligonucleotides of 12-15 bases may be used as amplification primers in PCR in order to obtain a particular nucleic acid molecule comprising the primers. Accordingly, a "substantial
15 portion" of a nucleotide sequence comprises enough of the sequence to afford specific identification and/or isolation of a nucleic acid molecule comprising the sequence. The instant specification teaches partial or complete amino acid and nucleotide sequences encoding one or more particular proteins. The skilled artisan, having the benefit of the sequences as reported herein, may now use all or
20 a substantial portion of the disclosed sequences for the purpose known to those skilled in the art. Accordingly, the instant invention comprises the complete sequences as reported in the accompanying Sequence Listing, as well as substantial portions of those sequences as defined above.
The term "complementary" describes the relationship between nucleotide
25 bases that are capable to hybridizing to one another. For example, with respect to DNA, adenosine is complementary to thymine and cytosine is complementary to guanine. Accordingly, the instant invention also includes isolated nucleic acid molecules that are complementary to the complete sequences as reported in the accompanying Sequence Listing as well as those substantially similar nucleic acid
30 sequences.
The term "percent identity", as known in the art, is a relationship between two or more polypeptide sequences or two or more polynucleotide sequences, as determined by comparing the sequences. In the art, "identity" also means the degree of sequence relatedness between polypeptide or polynucleotide sequences,
35 as the case may be, as determined by the match between strings of such sequences. "Identity" and "similarity" can be readily calculated by known methods, including but not limited to those described in: Computational
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Molecular Biology; Lesk, A. M., Ed.; Oxford University Press: New York, 1988; Biocomputing: Informatics and Genome Projects; Smith, D. W., Ed.; Academic
Press: New York, 1993; Computer Analysis of Sequence Data, Part I; Griffin, A.
M. and Griffin, H. G., Eds.; Humana Press: New Jersey, 1994; Sequence Analysis 5 in Molecular Biology; von Heinje, G., Ed.; Academic Press: New York, 1987; and
Sequence Analysis Primer; Gribskov, M. and Devereux, J., Eds.; Stockton Press: New York, 1991. Preferred methods to determine identity are designed to give the largest match between the sequences tested.
Methods to determine identity and. similarity are codified in publicly
10 available computer programs. Preferred computer program methods to determine identity and similarity between two sequences include, but are not limited to, the GCG Pileup program found in the GCG program package, using the Needleman and Wunsch algorithm with their standard default values of gap creation penalty=12 and gap extension penalty=4 (Devereux et al., Nucleic Acids Res.
15 12:387-395 (1984)), BLASTP, BLASTN, and FASTA (Pearson et al., Proc. Natl. Acad. Sci. USA 85:2444-2448 (1988). The BLASTX program is publicly available from NCBI and other sources (BLAST Manual. Altschul et al., Natl. Cent. Biotechnol. Inf., Natl. Library Med. (NCBI NLM) NIH, Bethesda, Md. 20894; Altschul et al., J. Mol. Biol. 215:403-410 (1990); Altschul et al, "Gapped
20 BLAST and PSI-BLAST: a new generation of protein database search programs", Nucleic Acids Res. 25:3389-3402 (1997)). Another preferred method to determine percent identity, is by the method of DNASTAR protein alignment protocol using the Jotun-Hein algorithm (Hein et al. Methods Enzymol. 183:626-645 (1990)). Default parameters for the Jotun-Hein method for alignments are: for multiple
25 alignments, gap penalty=l 1, gap length penalty=3; for pairwise alignments ktuple=6. As an illustration, by a polynucleotide having a nucleotide sequence having at least, for example, 95% "identity" to a reference nucleotide sequence it is intended that the nucleotide sequence of the polynucleotide is identical to the reference sequence except that the polynucleotide sequence may include up to five
30 point mutations per each 100 nucleotides of the reference nucleotide sequence. In other words, to obtain a polynucleotide having a nucleotide sequence at least 95% identical to a reference nucleotide sequence, up to 5% of the nucleotides in the reference sequence may be deleted or substituted with another nucleotide, or a number of nucleotides up to 5% of the total nucleotides in the reference sequence
35 may be inserted into the reference sequence. These mutations of the reference sequence may occur at the 5* or 3' terminal positions of the reference nucleotide sequence or anywhere between those terminal position, interspersed either
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individually among nucleotides in the reference sequence or in one or more contiguous groups within the reference sequence. Analogously, by a polypeptide
having an amino acid sequence havingat least, for example, 95% identity to a
reference amino acid sequence is intended that the amino acid sequence of the
5 polypeptide is identical to the reference sequence except that the polypeptide sequence may include up to five amino acid alterations per each 100 amino acids of the reference amino acid. In other words, to obtain a polypeptide having an amino acid sequence at least 95% identical to a reference amino acid sequence, up to 5% of the amino acid residues in the reference sequence may be deleted or
10 substituted with another amino acid, or a number of amino acids up to 5% of the total amino acid residues in the reference sequence may be inserted into the reference sequence. These alterations of the reference sequence may occur at the amino or carboxy terminal positions of the reference amino acid sequence or anywhere between those terminal positions, interspersed either individually
15 among residues in the reference sequence or in one or more contiguous groups within the reference sequence.
The term "homologous" refers to a protein or polypeptide native or naturally occurring in a given host cell. The invention includes microorganisms producing homologous proteins via recombinant DNA technology.
20 The term "percent homology" refers to the extent of amino acid sequence
identity between polypeptides. When a first amino acid sequence is identical to a second amino acid sequence, then the first and second amino acid sequences exhibit 100% homology. The homology between any two polypeptides is a direct function of
the total number of matching amino acids at a given position in either sequence, e.g.,
25 if half of the total number of amino acids in either of the two sequences are the same then the two sequences are said to exhibit 50% homology.
"Codon degeneracy" refers to divergence in the genetic code permitting variation of the nucleotide sequence without effecting the amino acid sequence of an encoded polypeptide. Accordingly, the instant invention relates to any nucleic
30 acid molecule that encodes all or a substantial portion of the amino acid sequence as set forth in SEQ ID NO:57. The skilled artisan is well aware of the "codon-bias" exhibited by a specific host cell in usage of nucleotide codons to specify a given amino acid. Therefore, when synthesizing a gene for improved expression in a host cell, it is desirable to design the gene such that its frequency of codon
3 5 usage approaches the frequency of preferred codon usage of the host cell. Modifications to the sequence, such as deletions, insertions, or substitutions in the sequence which produce silent changes that do not
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substantially affect the functional properties of the resulting protein molecule are also contemplated. For example, alteration in the gene sequence which reflect the
degeneracy of the genetic code, or which result in the production of a chemically
equivalent amino acid at a given site, are contemplated. Thus, a codon for the
5 amino acid alanine, a hydrophobic amino acid, may be substituted by a codon encoding another less hydrophobic residue, such as glycine, or a more hydrophobic residue, such as valine, leucine, or isoleucine. Similarly, changes which result in substitution of one negatively charged residue for another, such as aspartic acid for glutamic acid, or one positively charged residue for another, such
10 as lysine for arginine, can also be expected to produce a biologically equivalent product. Nucleotide changes which result in alteration of the N-terminal and C-terminal portions of the protein molecule would also not be expected to alter the activity of the protein. In some cases, it may in fact be desirable to make mutants of the sequence in order to study the effect of alteration on the biological activity
15 of the protein. Each of the proposed modifications is well within the routine skill in the art, as is determination of retention of biological activity in the encoded products. Moreover, the skilled artisan recognizes that sequences encompassed by this invention are also defined by their ability to hybridize, under stringent conditions (0.1X SSC, 0.1% SDS, 65 °C), with the sequences exemplified herein.
20 The term "expression" refers to the transcription and translation to gene
product from a gene coding for the sequence of the gene product.
The terms "plasmid", "vector", and "cassette" refer to an extra chromosomal element often carrying genes which are not part of the central metabolism of the cell, and usually in the form of circular double-stranded DNA
25 molecules. Such elements may be autonomously replicating sequences, genome integrating sequences, phage or nucleotide sequences, linear or circular, of a single- or double-stranded DNA or RNA, derived from any source, in which a number of nucleotide sequences have been joined or recombined into a unique construction which is capable of introducing a promoter fragment and DNA
30 sequence for a selected gene product along with appropriate 3' untranslated
sequence into a cell. "Transformation cassette" refers to a specific vector
containing a foreign gene and having elements in addition to the foreign gene that facilitates transformation of a particular host cell. "Expression cassette" refers to a specific vector containing a foreign gene and having elements in addition to the
3 5 foreign gene that allow for enhanced expression of that gene in a foreign host.
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Construction of Recombinant Organisms
Recombinant organisms containing the necessary genes that will encode the enzymatic pathway for the conversion of a carbon substrate to 1,3-propanediol
may be constructed using techniques well known in the art. Genes encoding
5 glycerol-3-phosphate dehydrogenase (GPD1), glycerol-3-phosphatase (GPP2), glycerol dehydratase (dhaBJ, dhaB2, and dhaB3), dehydratase reactivation factor (prfZ and or/X) and 1,3-propanediol oxidoreductase (dhaT) were isolated from a native host such as Klebsiellas* Saccharomyces and used to transform host strains such as £jg/EDH_5a7 ECL707, AA20Q, or KLP23.
10 Isolation of Genes
Methods of obtaining desired genes from a bacterial genome are common and well known in the art of molecular biology. For example, if the sequence of the gene is known, suitable genomic libraries may be created by restriction endonuclease digestion and may be screened with probes complementary to the
15 desired gene sequence. Once the sequence is isolated, the DNA may be amplified using standard primer directed amplification methods such as polymerase chain reaction (PCR) (U.S. 4,683,202) to obtain amounts of DNA suitable for transformation using appropriate vectors.
Alternatively, cosmid libraries may be created where large segments of
20 genomic DNA (35-45kb) may be packaged into vectors and used to transform
appropriate hosts. Cosmid vectors are unique in being able to accommodate large quantities of DNA. Generally cosmid vectors have at least one copy of the cos DNA sequence which is needed for packaging and subsequent circularization of the foreign DNA. In addition to the cos sequence these vectors will also contain
25 an origin of replication such as ColEl and drug resistance markers such as a gene resistant to ampicillin or neomycin. Methods of using cosmid vectors for the transformation of suitable bacterial hosts are well described in Sambrook, J. et al., Molecular Cloning: A Laboratory Manual. Second Edition (1989) Cold Spring Harbor Laboratory Press, herein incorporated by reference.
30 Typically to clone cosmids, foreign DNA is isolated and ligated, using the
appropriate restriction endonucleases, adjacent to the cos region of the cosmid vector. Cosmid vectors containing the linearized foreign DNA are then reacted with a DNA packaging vehicle such as bacteriophage. During the packaging process the cos sites are cleaved and the foreign DNA is packaged into the head
35 portion of the bacterial viral particle. These particles are then used to transfect suitable host cells such as E. coli. Once injected into the cell, the foreign DNA circularizes under the influence of the cos sticky ends. In this manner large
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segments of foreign DNA can be introduced and expressed in recombinant host cells.
Isolation And Cloning of Genes Encoding Glycerol Dehydratase (dhaBL dhaBL
and dhaB3) Dehydratase Reactivating Factors (orfZ and orfX). and 5 1.3-propanediol dehydrogenase (dhaT)
Cosmid vectors and cosmid transformation methods were used within the context of the present invention to clone large segments of genomic DNA from bacterial genera known to possess genes capable of processing glycerol to 1,3-propanediol. Specifically, genomic DNA from K. pneumoniae was isolated
10 by methods well known in the art and digested with the restriction enzyme Sau3 A for insertion into a cosmid vector Supercos 1 and packaged using Gigapackll packaging extracts. Following construction of the vector E. coli XL 1-Blue MR cells were transformed with the cosmid DNA. Transformants were screened for the ability to convert glycerol to 1,3-propanediol by growing the cells in the
15 presence of glycerol and analyzing the media for 1,3-propanediol formation.
Two of the 1,3-propanediol positive transformants were analyzed and the cosmids were named pKPl and pKP2. DNA sequencing revealed extensive homology to the glycerol dehydratase gene from C.freundii, demonstrating that these transformants contained DNA encoding the glycerol dehydratase gene.
20 Other 1,3-propanediol positive transformants were analyzed and the cosmids were named pKP4 and pKP5. DNA sequencing revealed that these cosmids carried DNA encoding a diol dehydratase gene.
Although the instant invention utilizes the isolated genes from within a Klebsiella cosmid, alternate sources of dehydratase genes and dehydratase
25 reactivation factor genes include, but are not limited to, Citrobacter, Clostridia and Salmonella (see Table 1).
26 Genes Encoding G3PDH and G3P Phosphatase
The present invention provides genes suitable for the expression of G3PDH and G3P phosphatase activities in a host cell.
30 Genes encoding G3PDH are known. For example, GPD1 has been
isolated from Saccharomyces and has the base sequence given by SEQ ID NO:53, encoding the amino acid sequence given in SEQ ID NO:54 (Wang et al., supra). Similarly, G3PDH activity has also been isolated from Saccharomyces encoded by GPD2 (Eriksson et al., Mol Microbiol. 17,95 (1995)).
35 For the purposes of the present invention it is contemplated that any gene
encoding a polypeptide responsible for NADH-dependent G3PDH activity is suitable wherein that activity is capable of catalyzing the conversion of
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dihydroxyacetone phosphate (DHAP) to glycerol-3-phosphate (G3P). Further, it is contemplated that any gene encoding the amino acid sequence of NADH-
dependent G3PDH's corresponding to the genes DAR1, GPD1, GPD2, GPD3, and
gpsA will be functional in the present invention wherein that amino acid sequence
5 may encompass amino acid substitutions, deletions or additions that do not alter the function of the enzyme. The skilled person will appreciate that genes
encoding G3PDH isolated from other sources will also be suitable for use in the
present invention. Genes encoding G3P phosphatase are known. For example, GPP2 has been isolated from Saccharomyces cerevisiae and has the base sequence
10 given by SEQ ID NO:55, which encodes the amino acid sequence given in SEQ ID NO:56 (Norbeck et al., J. Biol. Chem. 271, 13875 (1996)).
For the purposes of the present invention, any gene encoding a G3P phosphatase activity is suitable for use in the method wherein that activity is capable of catalyzing the conversion of glycerol-3-phosphate plus H20 to glycero1
15 plus inorganic phosphate. Further, any gene encoding the amino acid sequence o G3P phosphatase corresponding to the genes GPP2 and GPP1 will be functional in the present invention including any amino acid sequence that encompasses amino acid substitutions, deletions or additions that do not alter the function of th G3P phosphatase enzyme. The skilled person will appreciate that genes encoding
20 G3P phosphatase isolated from other sources will also be suitable for use in the
present invention -
Host Cells
Suitable host cells for the recombinant production of 1,3-propanediol may be either prokaryotic or eukaryotic and will be limited only by the host cell ability tc
25 express the active enzymes for the 1,3-propanediol pathway. Suitable host cells will be bacteria such as Citrobacter, Enterobacter, Clostridium, Klebsiella, Aerobacter, Lactobacillus, Aspergillus, Saccharomyces, Schizosaccharomyces, Zygosaccharomyces, Pichia, Kluyveromyces, Candida, Hansenula, Debaryomyces, Mucor, Toruiopsis, Methylobacter, Escherichia, Salmonella,
30 Bacillus, Streptomyces, and Pseudomonas. Preferred in the present invention are E. coli, E. blattae, Klebsiella, Citrobacter, and Aerobacter.
Microorganisms can be converted to a high titer 1,3-propanediol produce] by using the following general protocol.'*-
1. Determine the presence in a potential host organism of an endogenous
35 dhaTAikt activity that allows for the steady state concentration of a toxic
or inhibitory level of 3-HPA in the presence of 1-2 M 1,3-propanediol.
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2. If such an activity exists in the potential host organism, perform suitable mutagenisis to delete or inactivate this activity. Confirmation of a nonfunctional or deleted dhaTAM activity can be detected by the lack of 3-
HPA accumulation in the presence of 1-2 M 1,3-propanediol.
5 3. Express appropriate genes for a) glycerol production, if glycerol is not the
carbon source, b) glycerol dehydratase and the associated maintenance system, and c) yqhD. Considerations which would need to be taken with respect to certain microorganisms concern the expression or repression of endogenous dhaT-likc
10 enzymes under the conditions for 1,3-propanediol production. These might also include the presence of glycerol, glucose or anaerobisis.
11 Vectors and Expression Cassettes
The present invention provides a variety of vectors and transformation and expression cassettes suitable for the cloning, transformation and expression of
15 G3PDH, G3P phosphatase, dehydratase, and dehydratase reactivation factor into a suitable host cell. Suitable vectors will be those which are compatible with the microorganism employed. Suitable vectors can be derived, for example, from a bacteria, a virus (such as bacteriophage T7 or a M-13 derived phage), a cosmid, a yeast or a plant. Protocols for obtaining and using such vectors are known to
20 those in the art (Sambrook et al., Molecular Cloning: A Laboratory Manual -volumes 1,2, 3 (Cold Spring Harbor Laboratory: Cold Spring Harbor, NY, 1989)).
Typically, the vector or cassette contains sequences directing transcription and translation of the appropriate gene, a selectable marker, and sequences
25 allowing autonomous replication or chromosomal integration. Suitable vectors comprise a region 5' of the gene, which harbors transcriptional initiation controls, and a region 3' of the DNA fragment which controls transcriptional termination. It is most preferred when both control regions are derived from genes homologous to the transformed host cell. Such control regions need not be derived from the
30 genes native to the specific species chosen as a production host.
Initiation control regions, or promoters, which are useful to drive expression of the G3PDH and G3P phosphatase genes (DAR1 and GPP2, respectively) in the desired host cell are numerous and familiar to those skilled in the art. Virtually any promoter capable of driving these genes is suitable for the
35 present invention including but not limited to CYC1, HIS3, GAL1, GAL10,
ADHl, PGK, PH05, GAPDH, ADC1, TRP1, URA3, LEU2, ENO, and TPI
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(useful for expression in Saccharomyces); AOX1 (useful for expression in Pichia); and lac, trp, X?L, XPR, T7, tac, and trc (useful for expression in E. coli).
Termination control regions may also be derived from various genes native to the preferred hosts. Optionally, a termination site may be unnecessary;
5 however, it is most preferred if included.
For effective expression of the instant enzymes, DNA encoding the .
enzymes are linked operably through initiation codons to selected expression
control regions such that expression results in the formation of the appropriate
messenger RNA.
10 Particularly useful in the present invention are the vectors pDT29 and
pKP32 which are designed to be used in conjunction with pAH48. The essential elements of pDT29 and pKP32 are derived from the dha regulon isolated from Klebsiella pneumoniae. pDT29 contains the open reading frames dhaR, orJY, dhaT, orfiC, or/W, dhaBl, dhaB2, and dhaB3, nucleotide the sequences of which
15 are contained within SEQ ID NO: 1. pKP32 contains the same set of open reading frames as found on pDT29, from the same source, with the difference that pKP32 lacks the dhaT. pAH48 is the vehicle used for the introduction of DAR1 and GPP2 genes into the host cell and more specifically comprises the DAR1 and GPP2 genes isolated from Saccharomyces cerevisiae.
20 Transformation of Suitable Hosts and Expression of Genes for the Production of 1,3 -propanediol
Once suitable cassettes are constructed they are used to transform appropriate host cells. Introduction of the cassette containing the genes encoding G3PDH, G3P phosphatase, dehydratase, and dehydratase reactivation factor into
25 the host cell may be accomplished by known procedures such as by
transformation (e.g., using calcium-permeabilized cells, electroporation), or by transfection using a recombinant phage virus (Sambrook et al., supra).
In the present invention cassettes were used to transform the E. coli as fully described in the GENERAL METHODS and EXAMPLES.
30 Mutants
In addition to the cells exemplified, it is contemplated that the present method will be able to make use of cells having single or multiple mutations specifically designed to enhance the production of 1,3-propanediol. Cells that
normally divert a carbon feed stock into non-productive pathways, or that exhibit
35 significant catabolite repression could be mutated to avoid these phenotypic deficiencies. For example, many wild type cells are subject to catabolite repression from glucose and by-products in the media and it is contemplated that
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mutant strains of these wild type organisms, capable of 1,3-propanediol production that are resistant to glucose repression, would be particularly useful in
the present invention.
Methods of creating mutants are common and well known in the art. For
5 example, wild type cells may be exposed to a variety of agents such as radiation or chemical mutagens and then screened for the desired phenotype. When creating mutations through radiation either ultraviolet (UV) or ionizing radiation may be used. Suitable short wave UV wavelengths for genetic mutations will fall within the range of 200 nm to 300 run where 254 nm is preferred. UV radiation in this
10 wavelength principally causes changes within nucleic acid sequence from
guanidine and cytosine to adenine and thymidine. Since all cells have DNA repair mechanisms that would repair most UV induced mutations, agents such as caffeine and other inhibitors may be added to interrupt the repair process and maximize the number of effective mutations. Long wave UV mutations using
15 light in the 300 nm to 400 nm range are also possible but are generally not as effective as the short wave UV light unless used in conjunction with various activators such as psoralen dyes that interact with the DNA.
Mutagenesis with chemical agents is also effective for generating mutants and commonly used substances include chemicals that affect nonreplicating DNA
20 such as HN02 and NH2OH, as well as agents that affect replicating DNA such as acridine dyes, notable for causing frameshift mutations. Specific methods for creating mutants using radiation or chemical agents are well documented in the art. See for example Thomas D. Brock in Biotechnology: A Textbook of Industrial Microbiology, Second Edition (1989) Sinauer Associates, Inc.,
25 Sunderland, MA., or Deshpande, Mukund V., Appl. Biochem. Biotechnol. 36, 227 (1992), herein incorporated by reference.
After mutagenesis has occurred, mutants having the desired phenotype may be selected by a variety of methods. Random screening is most common where the mutagenized cells are selected for the ability to produce the desired
30 product or intermediate. Alternatively, selective isolation of mutants can be
performed by growing a mutagenized population on selective media where only resistant colonies can develop. Methods of mutant selection are highly developed and well known in the art of industrial microbiology. See for example Brock, Supra; DeMancilha et aL, Food Chem. 14,313 (1984).
3 5 The elimination of an undesired enzyme activity may be also
accomplished by disruption of the gene encoding the enzyme. Such methods are known to those skilled in tneart and are exemplified in Example 4 and Example 8.
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Alterations in the 1.3-propanediol Production Pathway
Representative Enzyme Pathway. The production of 1,3-propanediol from
glucose can be accomplished by the following series of steps. This series is representative of a number of pathways known to those skilled in the art and is
5 illustrated in Figure 5. Glucose is converted in a series of steps by enzymes of the glycolytic pathway to dihydroxyacetone phosphate (DHAP) and 3-phospho-glyceraldehyde (3-PG). Glycerol is then formed by either hydrolysis of DHAP to dihydroxyacetone (DHA) followed by reduction, or reduction of DHAP to glycerol 3-phosphate (G3P) followed by hydrolysis. The hydrolysis step can be
10 catalyzed by any number of cellular phosphatases, which are known to be nonspecific with respect to their substrates, or the activity can be introduced into the host by recombination. The reduction step can be catalyzed by a NAD+ (or NADP+) linked host enzyme or the activity can be introduced into the host by recombination. It is notable that the dha regulon contains a glycerol
15 dehydrogenase (E.C. 1.1.1.6) that catalyzes the reversible reaction of Equation 3.
Glycerol -» 3-HPA + H20 (Equation 1)
3-HPA + NADH + H+ -+ 1,3-PropanedioI + NAD+ (Equation 2)
Glycerol + NAD+ -> DHA + NADH + H+ (Equation 3)
20
Glycerol is converted to 1,3-propanediol via the intermediate 3-hydroxy-propionaldehye (3-HPA) as has been described in detail above. The intermediate 3-HPA is produced from glycerol, Equation 1, by a dehydratase enzyme that can be encoded by the host or can be introduced into the host by recombination. This
25 dehydratase can be glycerol dehydratase (E.C. 4.2.1.30), diol dehydratase
(E.C. 4.2.1.28) or any other enzyme able to catalyze this transformation. Glycerol dehydratase, but not diol dehydratase, is encoded by the dha regulon. 1,3-Propanediol is produced from 3-HPA, Equation 2, by aNAD+- (or NADP+) linked host enzyme or the activity can be introduced into the host by
30 recombination. This final reaction in the production of 1,3-propanediol can be catalyzed by 1,3-propanediol dehydrogenase (E.C. 1.1.1.202) or other alcohol dehydrogenases.
Mutations and transformations that affect carbon channeling. A variety of mutant microorganisms comprising variations in the 1,3-propanediol production pathway
3 5 will be useful in the present invention. For example the introduction of a
triosephosphate isomerase mutation (tpi-) into the microorganism of the present invention is an example of the use of a mutation to improve the performance by carbon channeling. Triosephosphate isomerase is the enzyme responsible for the
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conversion of DAHP to 3-phosphoglyceraldehyde, and as such allows the
diversion of carbon flow from the main pathway form glucose to glycerol and 1,3-propanediol (Figure 5). Thus, the deletion mutation {tpi-) enhances the overall
metabolic efficiency of the desired pathway over that described in the art.
5 Similarly, mutations which block alternate pathways for intermediates of the
1,3-propanediol production pathway would also be useful to the present invention. For example, the elimination of glycerol kinase prevents glycerol, formed from G3P by the action of G3P phosphatase, from being re-converted to G3P at the expense of ATP (Figure 5). Also, the elimination of glycerol dehydrogenase (for
10 example, gldA) prevents glycerol, formed from DHAP by the action of NADH-dependent glycerol-3-phosphate dehydrogenase, from being converted to dihydroxyacetone (Figure 5). Mutations can be directed toward a structural gene so as to impair or improve the activity of an enzymatic activity or can be directed
toward a regulatory gene, including promoter regions and ribosome binding sites,
15 so as to modulate the expression level of an enzymatic activity.
It is thus contemplated that transformations and mutations can be combined so as to control particular enzyme activities for the enhancement of 1,3-propanediol production. Thus, it is within the scope of the present invention to anticipate modifications of a whole cell catalyst which lead to an increased
20 production of 1,3-propanediol.
The present invention utilizes a preferred pathway for the production of 1,3-propanediol from a sugar substrate where the carbon flow moves from glucose to DHAP, G3P, Glycerol, 3-HPA and finally to 1,3-propanediol. The present production strains have been engineered to maximize the metabolic efficiency of
25 the pathway by incorporating various deletion mutations that prevent the diversion of carbon to non-productive compounds. Glycerol may be diverted from conversion to 3HPA by transformation to either DHA or G3P via glycerol dehydrogenase or glycerol kinase as discussed above (Figure 5). Accordingly, the
present production strains contain deletion mutations in the gldA and glpK genes. 30 Similarly DHAP may be diverted to 3-PG by triosephosphate isomerase, thus the
present production microorganism also contains a deletion mutation in this gene. The present method additionally incorporates a dehydratase enzyme for the conversion of glycerol to 3 HP A, which functions in concert with the reactivation factor, encoded by orjX and orfZ of the dha regulon (Figure 5). Although
3 5 conversion of the 3HP A to 1,3-propanediol is typically accomplished via a 1,3-propanediol oxidoreductase, the present method utilizes a non-specific catalytic activity that produces greater titers and yields of the final product,
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1,3-propanediol (Figure 5). In such a process, titers of 1,3-propanediol of at least 10 g/L are achieved, where titers of 200 g/L are expected.
Alternatively, an improved process for 1,3-propanediol production may
utilize glycerol or dihydroxyacetone as a. substrate where the pathway comprises
5 only the last three substrates, glycerol —> 3HPA —> 1,3-propanediol. In such a
process, the oxidoreductase is again eliminated in favor of the non-specific
catalytic activity, (expected to be an alcohol dehydrogenase), however the need
for deletion mutations are nullified by the energy considerations of adding glycerol to the culture. In such as process titers of 1,3-propanediol of at least
10 71 g/L are achieved where titers of 200 g/L are expected.
Similarly it is within the scope of the invention to provide mutants of wildtype microorganisms that have been modified by the deletion or mutation of the dhaT activity to create improved 1,3-propandiol producers. For example, microorganisms, which naturally contain all the elements of the dha regulon, may
15 be manipulated so as to inactivate the dhaT gene encoding the 1,3-propandiol oxidoreductase activity. These microorganisms will be expected to produce higher yields and titers of 1,3-propanediol, mediated by the presence of an endogenous catalytic activity, expected to be an alcohol dehydrogenase. Examples of such microorganisms include but are not limited to Klebsiella sp.,
20 Citrobacter sp., and Clostridium sp. Media and Carbon Substrates
Fermentation media in the present invention must contain suitable carbon substrates. Suitable substrates may include but are not limited to monosaccharides such as glucose and fructose, oligosaccharides such as lactose or sucrose,
25 polysaccharides such as starch or cellulose or mixtures thereof and unpurified mixtures from renewable feedstocks such as cheese whey permeate, cornsteep liquor, sugar beet molasses, and barley malt. Additionally the carbon substrate may also be one-carbon substrates such as carbon dioxide, or methanol for which metabolic conversion into key biochemical intermediates has been demonstrated.
30 Glycerol production from single carbon sources (e.g., methanol, formaldehyde or formate) has been reported in methylotrophic yeasts (K. Yamada et al., Agric. Biol. Chem. 53(2), 541-543 (1989)) and in bacteria (Hunter et. al., Biochemistry 24,4148-4155 (1985)). These microorganisms can assimilate single carbon compounds, ranging in oxidation state from methane to formate, and produce
35 glycerol. The pathway of carbon assimilation can be through ribulose
monophosphate, through serine, or through xylulose-momophosphate (Gottschalk,
Bacterial Metabolism. Second Edition, Springer-Verlag: New York (1986)). The
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ribulose monophosphate pathway involves the condensation of formate with ribulose-5-phosphate to form a 6-carbon sugar that becomes fructose and
eventually the three-carbon product glyceraldehyde-3-phosphate. Likewise, the
serine pathway assimilates the one-carbon compound into the glycolytic pathway
5 via methylenetetrahydrofolate.
In addition to one and two carbon substrates, methylotrophic microorganisms are also known to utilize a number of other carbon-containing compounds such as methylamine, glucosamine and a variety of amino acids for metabolic activity. For example, methylotrophic yeast are known to utilize the
10 carbon from methylamine to form trehalose or glycerol (Bellion et al., Microb. Growth CI Compd, [Int. Symp.], 7th (1993), 415-32. Editor(s): Murrell, J. Collin; Kelly, Don P. Publisher: Intercept, Andover, UK). Similarly, various species of Candida will metabolize alanine or oleic acid (Suiter et al., Arch. Microbiol. 153(5), 485-489 (1990)). Hence, it is contemplated that the source of
15 carbon utilized in the present invention may encompass a wide variety of carbon-containing substrates and will only be limited by the choice of microorganism or process.
Although it is contemplated that all of the above mentioned carbon substrates and mixtures (co-feed) thereof are suitable in the present invention,
20 preferred carbon substrates are glucose, fructose, sucrose, or methanol where the process intends to produce an endogenous glycerol, and glycerol or dihydroxyacetone where the process anticipates a glycerol or dihydroxyacetone feed.
In addition to an appropriate carbon source, fermentation media must
25 contain suitable minerals, salts, cofactors, buffers and other components, known to those skilled in the art, suitable for the growth of the cultures and promotion of the enzymatic pathway necessary for 1,3-propanediol production. Particular attention is given to Co(II) salts and/or vitamin Bj2 or precursors thereof.
Adenosyi-cobalamin (coenzyme B12) is an essential cofactor for
30 dehydratase activity. Synthesis of coenzyme B12 is found in prokaryotes, some of which are able to synthesize the compound de novo, for example, Escherichia blattae, Klebsiella species, Citrobacter species, and Clostridium species, while others can perform partial reactions. E. coli, for example, cannot fabricate the corrin ring structure, but is able to catalyze the conversion of cobinamide to
35 corrinoid and can introduce the 5'-deoxyadenosyl group. Thus, it is known in the art that a coenzyme Bj2 precursor, such as vitarnin Bj2, need be provided in E. coli fermentations.-
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Vitamin B12 additions to E. coli fermentations may be added continuously, at a constant rate or staged as to coincide with the generation of cell mass, or may be added in single or multiple bolus additions. Preferred ratios of vitamin BI2 (mg) fed to cell mass (OD550) are from 0.06 to 0.60. Most preferred ratios of
5 vitamin B12 (mg) fed to cell mass (OD550) are from 0.12 to 0.48.
Although vitamin B 12 is added to the transformed E. coli of the present invention it is contemplated that other microorganisms, capable of de novo Bj2 biosynthesis will also be suitable production cells and the addition of B12 to these microorganisms will be unnecessary.
10 Culture Conditions:
Typically cells are grown at 35 °C in appropriate media. Preferred growth media in the present invention are common commercially prepared media such as Luria Bertani (LB) broth, Sabouraud Dextrose (SD) broth or Yeast medium (YM) broth. Other defined or synthetic growth media may also be used and the
15 appropriate medium for growth of the particular microorganism will be known by someone skilled in the art of microbiology or fermentation science. The use of agents known to modulate catabolite repression directly or indirectly, e.g., cyclic adenosine 2':3'-monophosphate, may also be incorporated into the reaction media. Similarly, the use of agents known to modulate enzymatic activities (e.g., methyl
20 viologen) that lead to enhancement of 1,3-propanediol production may be used in conjunction with or as an alternative to genetic manipulations.
Suitable pH ranges for the fermentation are between pH 5.0 to pH 9.0, where pH 6.0 to pH 8.0 is preferred as the initial condition.
Reactions may be performed under aerobic or anaerobic conditions where 25 anaerobic or microaerobic conditions are preferred.
Fed-batch fermentations may be performed with carbon feed, for example, glucose, limited or excess. Batch and Continuous Fermentations:
The present process employs a batch method of fermentation. Classical
30 batch fermentation is a closed system where the composition of the media is set at the beginning of the fermentation and is not subject to artificial alterations during the fermentation. Thus, at the beginning of the fermentation the media is inoculated with the desired microorganism or microorganisms and fermentation is permitted to occur adding nothing to the system. Typically, however,"batch"
3 5 fermentation is batch with respect to the addition of carbon source and attempts are often made at controlling factors such as pH and oxygen concentration. In batch systems the metabolite and biomass compositions of the system change
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constantly up to the time the fermentation is stopped. Within batch cultures cells moderate through a static lag phase to a high growth log phase and finally to a stationary phase where growth rate is diminished or halted. If untreated, cells in the stationary phase will eventually die. Cells in log phase generally are
5 responsible for the bulk of production of end product or intermediate.
A variation on the standard batch system is the Fed-Batch system. Fed-Batch fermentation processes are also suitable in the present invention and comprise a typical batch system with the exception that the substrate is added in increments as the fermentation progresses. Fed-Batch systems are useful when
10 catabolite repression is apt to inhibit the metabolism of the cells and where it is desirable to have limited amounts of substrate in the media. Measurement of the actual substrate concentration in Fed-Batch systems is difficult and is therefore estimated on the basis of the changes of measurable factors such as pH, dissolved oxygen and the partial pressure of waste gases such as CO2. Batch and Fed-Batch
15 fermentations are common and well known in the art and examples may be found in Brock, supra.
Although the present invention is performed in batch mode it is contemplated that the method would be adaptable to continuous fermentation methods. Continuous fermentation is an open system where a defined
20 fermentation media is added continuously to a bioreactor and an equal amount of conditioned media is removed simultaneously for processing. Continuous
fermentation generally maintains the cultures at a constant high density where
cells are primarily in log phase growth.
Continuous fermentation allows for the modulation of one factor or any
25 number of factors that affect cell growth or end product concentration. For
example, one method will maintain a limiting nutrient such as the carbon source or nitrogen level at a fixed rate and allow all other parameters to moderate. In other systems a number of factors affecting growth can be altered continuously while the cell concentration, measured by media turbidity, is kept constant.
30 Continuous systems strive to maintain steady state growth conditions and thus the cell loss due to media being drawn off must be balanced against the cell growth rate in the fermentation. Methods of modulating nutrients and growth factors for continuous fermentation processes as well as techniques for maximizing the rate of product formation are well known in the art of industrial microbiology and a
35 variety of methods are detailed by Brock, supra.
It is contemplated that the present invention may be practiced using batch, fed-batch or continuous processes and that any known mode of fermentation
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would be suitable. Additionally, it is contemplated that cells may be immobilized on a substrate as whole cell catalysts and subjected to fermentation conditions for
1,3-propanediol production.
Identification and purification of 1.3-propanediol:
5 Methods for the purification of 1,3-propanediol from fermentation media
are known in the art. For example, propanediols can be obtained from cell media by subjecting the reaction mixture to extraction with an organic solvent, distillation, and column chromatography (U.S. 5,356,812). A particularly good organic solvent for this process is cyclohexane (U.S. 5,008,473).
10 1,3-Propanediol may be identified directly by submitting the media to high
pressure liquid chromatography (HPLC) analysis. Preferred in the present invention is a method where fermentation media is analyzed on an analytical ion exchange column using a mobile phase ofO.OlN sulfuric acid in an isocratic fashion.
15 EXAMPLES
GENERAL METHODS
Procedures for phosphorylations, ligations and transformations are well known in the art. Techniques suitable for use in the following examples may be found in Sambrook, J. et al., Molecular Cloning: A Laboratory Manual. Second
20 Edition, Cold Spring Harbor Laboratory Press (1989).
Materials and methods suitable for the maintenance and growth of bacterial cultures are well known in the art. Techniques suitable for use in the following examples may be found in Manual of Methods for General Bacteriology (Phillipp Gerhardt, R. G. E. Murray, Ralph N. Costilow, Eugene W. Nester, Willis
25 A. Wood, Noel R. Krieg and G. Briggs Phillips, eds), American Society for
Microbiology, Washington, D.C. (1994) or Thomas D. Brock in Biotechnoloev: A Textbook of Industrial Microbiology. Second Edition (1989) Sinauer Associates, Inc., Sunderland, MA. All reagents and materials used for the growth and maintenance of bacterial cells were obtained from Aldrich Chemicals
30 (Milwaukee, WI), DIFCO Laboratories (Detroit, MI), GIBCO/BRL (Gaithersburg, MD), or Sigma Chemical Company (St. Louis, MO) unless otherwise specified.
The meaning of abbreviations is as follows: "h" means hour(s), "min" means minute(s), "sec" means second(s), "d" means day(s), "mL" means
milliliters, "L" means liters, 50 amp is 50 jig/mL ampicillin, and LB-50 amp is
35 Luria-Bertani broth containing 50 μg/mL ampicillin.
Within the tables the following abbreviations are used. "Con." is conversion, "Sel." is selectivity based on carbon, and "nd" is not detected.
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Strains and vectors used and constructed in the following examples are listed in the chart below:

STRAIN/PLASMID DELETION ORF/GENE
KLP23 gldA glpK
RJ8m gldA glpK Tpi
pAH48 GPP2 DARl
pDT29 dhaRorfYdhaTorfXorfWdhaBldhaB2dhaB3orfZ
pKP32 dhaR orJY orpC orJWdhaBl dhaB2 dhaB3 orfl
5 ENZYME ASSAYS
Assays for dehydratase enzymes:
Dehydratase activity in cell-free extracts was determined using either glycerol or 1,2-propanediol as substrate. Typically, cell-free extracts were prepared by cell disruption using a french press followed by centrifugation of the
10 cellular debris. The assay, based on the reaction of aldehydes with
methylbenzo-2-thiazolone hydrazone, has been described by Forage and Foster {Biochim. Biophys. Acta 569, 249 (1979)).
Honda et al. (J. Bacteriol. 143, 1458 (1980)) disclose an assay that measures the reactivation of dehydratases. Dehydratase activity was determined
15 in toluenized whole cells, with and without ATP, using either glycerol or
1,2-propanediol as substrate. Reactivation was determined by the ratio of product formation with versus without the ATP addition. Product formation (3-HPA or
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propionaldehyde when glycerol or 1,2-propanediol is used as substrate,
respectively) was measured directly, using HPLC, or indirectly, using the methyIbenzo-2-thiazolone hydrazone reagent. Alternatively, product formation was determined by coupling the conversion of the aldehyde to its respective
5 alcohol using a NADH linked alcohol dehydrogenase and monitoring the disappearance of NADH. Assays for 1.3-propanediol oxidoreductase:
The activity of 1,3-propanediol oxidoreductase, sometimes referred to as 1,3-propanediol dehydrogenase, was determined for cell-free extracts in solution
10 or in slab gels using 1,3-propanediol and NAD+ as substrates has been described (Johnson and Lin, J. Bacterial. 169, 2050 (1987)). Alternatively, the conversion of 3-HPA and NADH to 1,3-propanediol and NAD+ was determined by the disappearance of NADH. The slab gel assay has the potential advantage of separating the activity of 1,3-propanediol oxidoreductase (dhaT) from that of non-
15 specific alcohol dehydrogenases by virtue of size separation. The native
molecular weights of 1,3-propanediol oxidoreductases (dhaT) from Citrobacter frendii, Klebsiella pneumoniae, and Clostridium pasteurianum are unusually large, on the order of 330,000 to 440,000 daltons. Lactobacillus brevis and Lactobacillus buchneri contain dehydratase associated 1,3-propanediol
20 oxidoreductases with properties similar to those of known 1,3-propanediol oxidoreductases (dhaT). Assays for glycerol 3-phosphate dehydrogenase activity:
A procedure was used asrhodified below" from a method published by Bell et al. (J. Biol Chem. 250, 7153 (1975)). This method involved incubating a cell-
25 free extract sample in a cuvette that contained 0.2 mM NADH, 2.0 mM
dihydroxyacetone phosphate (DHAP), and enzyme in 0.1 M Tris/HCl, pH 7.5 buffer with 5 mM DTT, in a total volume of 1.0 mL at 30 °C. A background rate of the reaction of enzyme and NADH was first determined at 340 nm for at least 3 min. The second substrate, DHAP, was subsequently added and the absorbance
30 change over time was further monitored for at least 3 min. G3PDH activity was defined by subtracting the background rate from the gross rate. Assay for glvcerol-3-phosphatase activity.
The assay for enzyme activity was performed by incubating the extract with an organic phosphate substrate in a bis-Tris or MES and magnesium buffer,
35 pH 6.5. The substrate used was either 1-a-glycerol phosphate, or d,l-cc-glycerol phosphate. The final concentrations of the reagents in the assay are: buffer (20 mM, bis-Tris or 50 mM MES); MgCl2 (10 mM); and substrate (20 mM). If
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the total protein in the sample was low and no visible precipitation occurs with an acid quench, the sample was conveniently assayed in the cuvette. This method involved incubating an enzyme sample in a cuvette that contained 20 mM substrate (50 uL, 200 mM), 50 mM MES, 10 mM MgCl2, pH 6.5 buffer. The
5 final phosphatase assay volume was 0.5 mL. The enzyme-containing sample was added to the reaction mixture; the contents of the cuvette were mixed and then the cuvette was placed in a circulating water bath at T = 37 °C for 5 to 120 min, the length of time depending on whether the phosphatase activity in the enzyme sample ranged from 2 to 0.02 U/mL. The enzymatic reaction was quenched by
10 the addition of the acid molybdate reagent (0.4 mL). After the Fiske SubbaRow reagent (0.1 mL) and distilled water (1.5 mL) were added, the solution was mixed and allowed to develop. After 10 min, to allow full color development, the absorbance of the samples was read at 660 nm using a Cary 219 UV/vis spectrophotometer. The amount of inorganic phosphate released was compared to
15 a standard curve that was prepared by using a stock inorganic phosphate solution (0.65 mM) and preparing 6 standards with final inorganic phosphate concentrations ranging from 0.026 to 0.130 (j.mol/mL. Assay for glycerol kinase activity:
An appropriate amount of enzyme, typically a cell-free crude extract, was
20 added to a reaction mixture containing 40 mM ATP, 20 mM MgS04,21 mM
uniformly 13C labelled glycerol (99%, Cambridge Isotope Laboratories), and 0.1 M Tris-HCl, pH 9 for 75 min at 25 °C. The conversion of glycerol to glycerol 3-phosphate was detected by 13C-NMR (125 MHz): glycerol (63.11 ppm, 6, J = 41 Hz and 72.66 ppm, t, J= 41 Hz); glycerol 3-phosphate (62.93 ppm, 5,
25 J = 41 Hz; 65.31 ppm, br d, J = 43 Hz; and 72.66 ppm, dt, J= 6, 41 Hz). NADH-linked glycerol dehydrogenase assay:
NADH -linked glycerol dehydrogenase activity igldA) in cell-free extracts from E. coli strains was determined after protein separation by non-denaturing polyacrylamide gel electrophoresis. The conversion of glycerol plus NAD+ to
30 dihydroxyacetone plus NADH was coupled with the conversion of 3-[4,5-
dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) to a deeply colored formazan, using phenazine methosulfate (PMS) as mediator (Tang et al., J.Bacteriol.]40,m(\997)).
Electrophoresis was performed in duplicate by standard procedures using
3 5 native gels (8-16% TG, 1.5 mm, 15 lane gels from Novex, San Diego, CA).
Residual glycerol was removed from the gels by washing 3x with 50 mM Tris or potassium carbonate buffer, pH 9 for 10 min. The duplicate gels were developed,
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with and without glycerol (approximately 0.16 M final concentration), in 15 mL of assay solution containing 50 mM Tris or potassium carbonate, pH 9,60 mg
ammonium sulfate, 75 mg NAD+, 1.5 mg MTT, and 0.5 mg PMS.
The presence or absence of NADH -linked glycerol dehydrogenase activity
5 in E. coli strains (gldA) was also determined, following polyacrylamide gel electrophoresis, by reaction with polyclonal antibodies raised to purified K. pneumoniae glycerol dehydrogenase (dhaD). Isolation and identification of 1.3-propanediol:
The conversion of glycerol to 1,3-propanediol was monitored by HPLC.
10 Analyses were performed using standard techniques and materials available to one of skill in the art of chromatography. One suitable method utilized a Waters Maxima 820 HPLC system using UV (210 nm) and RJ detection. Samples were injected onto a Shodex SH-1011 column (8 mm x 300 mm, purchased from Waters, Milford, MA) equipped with a Shodex SH-101 IP precolumn (6 mm x
15 50 mm), temperature controlled at 50 °C, using 0.01 N H2S04 as mobile phase at a flow rate of 0.5 mL/min. When quantitative analysis was desired, samples were prepared with a known amount of trimethylacetic acid as external standard. Typically, the retention times of glucose (RI detection), glycerol, 1,3-propanediol (RI detection), and trimethylacetic acid (UV and RI detection) were 15.27 min,
20 20.67 min, 26.08 min, and 35.03 min, respectively.
Production of 1,3-propanediol was confirmed by GC/MS. Analyses were performed using standard techniques and materials available to one of skill in the art of GC/MS. One suitable method utilized a Hewlett Packard 5890 Series II gas chromatograph coupled to a Hewlett Packard 5971 Series mass selective detector
25 (EI) and a HP-INNOWax column (30 m length, 0.25 mm i.d., 0.25 micron film thickness). The retention time and mass spectrum of 1,3-propanediol generated were compared to that of authentic 1,3-propanediol (m/e: 57,58).
An alternative method for GC/MS involved derivatization of the sample. To 1.0 mL of sample (e.g., culture supernatant) was added 30 uL of concentrated
30 (70% v/v) perchloric acid. After mixing, the sample was frozen and lyophilized. A 1:1 mixture of bis(trimethylsilyl)trifluoroacetamide:pyridine (300 uL) was added to the lyophilized material, mixed vigorously and placed at 65 °C for one h. The sample was clarified of insoluble material by centrifugation. The resulting liquid partitioned into two phases, the. upper of which was used for analysis. The
35 sample was chromatographed on a DB-5 column (48 m, 0.25 mm I.D., 0.25 urn film thickness; from J&W Scientific) and the retention time and mass spectrum of the 1,3-propanediol derivative obtained from culture supernatants were compared
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to that obtained from authentic standards. The mass spectra of TMS-derivatized 1,3-propanediol contains the characteristic ions of 205,177,130 and 115 AMU. Cell Lvsis:
Cell lysis was estimated by measuring the extracellular soluble protein
5 concentration in the fermentation broth. Fermenter samples were centrifuged in a desktop centrifuge (typically, 3-5 min at 12,000 rpm in an Eppendorf, Model 5415C micro centrifuge) in order to separate cells. The resulting supernatant was analyzed for protein concentration by the Bradford method using a commercially available reagent (Bio-Rad Protein Assay, Bio-Rad, Hercules, CA).
10 Viability:
Cell viability was determined by plating, at appropriate dilutions, cells
obtained from the fermenter on non-selective LB agar plates. Cell viability
between fermenter experiments is compared by using the ratio of viable cells per
mL of fermenter broth divided by OD550 (AU).
15 EXAMPLE 1
CLONING AND TRANSFORMATION OF E. COLI HOST CELLS WITH COSMID DNA FOR THE EXPRESSION OF 1.3-PROPANEDIOL Media:
Synthetic S12 medium was used in the screening of bacterial transformants 20 for the ability to make 1,3-propanediol. S12 medium contains: l0mM
ammonium sulfate, 50 mM potassium phosphate buffer, pH 7.0, 2 mM MgCl2, 0.7 mM CaCl2, 50 μM MnCl2, 1 uM FeCl3,1 μM ZnCl, 1.7 μM CuS04,2.5 μM CoCl2, 2.4 p.M Na2Mo04, and 2 μM thiamine hydrochloride.
Medium A used for growth and fermentation consisted of: 10 mM
25 ammonium sulfate; 50 mM MOPS/KOH buffer, pH 7.5; 5 mM potassium
phosphate buffer, pH 7.5; 2 mM MgCl2; 0.7 mM CaCl2; 50 uM MnCl2; 1 uM FeCl3; 1 μM ZnCl; 1.72 μM CuS04; 2.53 μM CoCl2; 2:42 p.M Na2Mo04; 2 μM thiamine hydrochloride; 0.01% yeast extract; 0.01% casamino acids; 0.8 ug/rnL vitamin Bj2; and 50 μg/mL amp. Medium A was supplemented with either 0.2%
30 glycerol or 0.2% glycerol plus 0.2% D-glucose as required. Cells:
Klebsiella pneumoniae ECL2106 (Ruch et al., J. Bacteriol. 124, 348
(1975)), also known in the literature as K. aerogenes oiAerobacter aerogenes, was obtained from E. C. C. Lin (Harvard Medical School, Cambridge, MA) and
35 was maintained as a laboratory culture.
Klebsielh^newnomae ATCC 25955 was purchased from American Type " Culture Collection (Manassas, VA).
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E. coli DH5cc was purchased from Gibco/BRL and was transformed with the cosmid DNA isolated from Klebsiella pneumoniae ATCC 25955 containing a
gene coding for either a glycerol or diol dehydratase enzyme. Cosmids containing the glycerol dehydratase were identified as pKPl and pKP2 and cosmid
5 containing the diol dehydratase enzyme were identified as pKP4. Transformed DH5α cells were identified as DH5α-pKPl, DH5α-pKP2, and DH5α-pKP4.
& coli ECL707 (Sprenger et al.s J. Gen. Microbiol. 135,1255 (1989)) was obtained from E. C. C. Lin (Harvard Medical School, Cambridge, MA) and was similarly transformed with cosmid DNA from Klebsiella pneumoniae. These
10 transformants were identified as ECL707-pKP 1 and ECL707-pKP2, containing the glycerol dehydratase gene and ECL707-pKP4 containing the diol dehydratase gene.
E. coli AA200 containing a mutation in the tpi gene (Anderson et al., J. Gen. Microbiol. 62,329 (1970)) was purchased from the E. coli Genetic Stock
15 Center, Yale University (New Haven, CT) and was transformed with Klebsiella cosmid DNA to give the recombinant microorganisms AA200-pKPl and AA200-pKP2, containing the glycerol dehydratase gene, and AA200-pKP4, containing the diol dehydratase gene. DH5α:
20 Six transformation plates containing approximately 1,000 colonies of
E. coli XL 1-Blue MR transfected with K pneumoniae DNA were washed with 5 mL LB medium and centrifuged. The bacteria were pelleted and resuspended in 5 mL LB medium + glycerol. An aliquot (50 uL) was inoculated into a 15 mL tube containing S12 synthetic medium with 0.2% glycerol + 400 ng per mL of
25 vitamin B12 + 0.001% yeast extract + 50 amp. The tube was filled with the medium to the top and wrapped with parafilm and incubated at 30 °C. A slight turbidity was observed after 48 h. Aliquots, analyzed for product distribution as described above at 78 h and 132 h, were positive for 1,3-propanediol, the later time points containing increased amounts of 1,3-propanediol.
30 The bacteria, testing positive for 1,3-propanediol production, were serially
diluted and plated onto LB-50 amp plates in order to isolate single colonies. Forty-eight single colonies were isolated and checked again for the production of 1,3-propanediol. Cosmid DNA was isolated from 6 independent clones and transformed into E. coli strain DH5a. The transformants were again checked for
35 the production of 1,3-propanediol. Two transformants were characterized further and designated as DH5ct-pKPl and DH5α-pKP2
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A 12.1 kb EcoRI-Sall fragment from pKPl, subcloned into pIBDl (BI Biosystem, New Haven, CT), was sequenced and termed pHK28-26 (SEQ ID
NO: 1). Sequencing revealed the loci of the relevant open readmg frames of the dha operon encoding glycerol dehydratase and genes necessary for regulation.
5 Referring to SEQ ID NO: 1, a fragment of the open reading frame for dhaKl encoding dihydroxyacetone kinase is found at bases 1-399 (complement); the open reading frame dhaD encoding glycerol dehydrogenase is found at bases 1010-2107; the open reading frame dhaR encoding the repressor is found at bases 2209-4134; the open reading frame orJW, encoding a protein of unknown function
10 is found at bases 4112-4642 (complement); the open reading frame orflC encoding a dehydratase reactivation protein is found at bases 4643-4996 (complement); the
open reading frame dhaT encoding 1,3-propanediol oxidoreductase is found at bases 5017-6180 (complement); the open reading frame or/Y, encoding a protein of unknown function is found at bases 6202-6630 (complement); the open reading
15 frame dhaBl encoding the alpha subunit glycerol dehydratase is found at bases 7044-8711; the open reading frame dhaB2 encoding the beta subunit glycerol dehydratase is found at bases 8724-9308; the open reading frame dhaB3 encoding the gamma subunit glycerol dehydratase is found at bases 9311-9736; the open reading frame dhaBX, encoding a dehydratase reactivation protein is found at
20 bases 9749-11572; and a fragment of the open reading frame for glpF encoding a glycerol uptake facilitator protein is found at bases 11626-12145.
Single colonies of E. coli XLl-Blue MR transfected with packaged cosmid DNA from K. pneumoniae were inoculated into microtiter wells containing 200 μL of S15 medium (ammonium sulfate, 10 mM; potassium phosphate buffer,
25 pH 7.0, 1 mM; MOPS/KOH buffer, pH 7.0, 50 mM; MgCl2,2 mM; CaCl2,
0.7 mM; MnCl2, 50 μM; FeCl3, 1 μM; ZnCl, 1 μM; CuS04, 1.72 μM; CoCl2, 2.53 μM; Na2Mo04,2.42 μM; and thiamine hydrochloride, 2 μM) + 0.2% glycerol + 400 ng/mL of vitamin Bj2 + 0.001% yeast extract + 50 μg/mL ampicillin. In addition to the microtiter wells, a master plate containing
30 LB-50 amp was also inoculated. After 96 h, 100 μL was withdrawn and
centrifuged in a Rainin microfuge tube containing a 0.2 micron nylon membrane filter. Bacteria were retained and the filtrate was processed for HPLC analysis. Positive clones demonstrating 1,3-propanedioLproduction were identified after
screening approximately 240 colonies. Three positive clones were identified, two
35 of which had grown on LB-50 amp and one of which had not. A single colony, isolated from one of the two positive clones grown on LB-50 amp and verified for the production of 1,3-propanediol, was designated as pKP4. Cosmid DNA was
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isolated from E. coli strains containing pKP4 and E. coli strain DH5a was
transformed. An independent transformant, designated as DH5a-pKP4, was
verified for the production of 1,3-propanediol.
ECL707:
5 E. coli strain ECL707 was transformed with cosmid K. pneumoniae DNA
corresponding to one of pKPl, pKP2, pKP4 or the Supercos vector alone and named ECL707-pKPl, ECL707-pKP2, ECL707-pKP4, and ECL707-SC, respectively. ECL707 is defective in glpK, gld, andptsD which encode the ATP-dependent glycerol kinase, NAD+-linked glycerol dehydrogenase, and
10 enzyme II for dihydroxyacetone of the phosphoenolpyruvate-dependent phosphotransferase system, respectively.
Twenty single colonies of each cosmid transformation and five of the Supercos vector alone (negative control) transformation, isolated from LB-50 amp plates, were transferred to a master LB-50 amp plate. These isolates were also
15 tested for their ability to convert glycerol to 1,3-propanediol in order to determine if they contained dehydratase activity. The transformants were transferred with a sterile toothpick to microtiter plates containing 200 uL of Medium A supplemented with either 0.2% glycerol or 0.2% glycerol plus 0.2% D-glucose. After incubation for 48 h at 30 °C, the contents of the microtiter plate wells were
20 filtered through a 0.45 micron nylon filter and chromatographed by HPLC. The results of these tests are given in Table 2.
TABLE 2 ...
Conversion of glycerol to 1,3-propanediol by transformed ECL707
transformant glycerol* glycerol plus glucose*
ECL707-pKPl 19/20 19/20
ECL707-pKP2 18/20 20/20
ECL707-pKP4 0/20 20/20
ECL707-sc 0/5 0/5
* (Number of positive isolates/number of isolates tested)
AA200:
25 E. coli strain AA200 was transformed with cosmid K. pneumoniae DNA
corresponding to one of pKPl, pKP2, pKP4 and the Supercos vector alone and
named AA200-pKPl, AA200-pKP2, AA200-pKP4, and AA200-sc, respectively. Strain AA200 is defective in triosephosphate isomerase (tpf).
Twenty single colonies of each cosmid transformation and five of the 30 empty vector transformation were isolated and tested for their ability to convert
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glycerol to 1,3-propanediol as described for E. coli strain ECL707. The results of these tests are given in Table 3.
TABLE 3
Conversion of glycerol to 1,3-propanediol by transformed AA2Q0
transformant glycerol* glycerol plus glucose*
AA200-pKPl 17/20 17/20
AA200-pKP2 17/20 17/20
AA200-pKP4 2/20 16/20
AA200-sc 0/5 0/5
*(Number of positive isolates/number of isolates tested)
5 EXAMPLE 2
ENGINEERING OF GLYCEROL KINASE MUTANTS OF E. COLI FM5 FOR PRODUCTION OF GLYCEROL FROM GLUCOSE Construction of integration plasmid for glycerol kinase gene replacement in E. coli FM5:
10 E. coli FM5 (ATCC 53911) genomic DNA was prepared using the
Puregene DNA Isolation Kit (Gentra Systems, Minneapolis, MN). A 1.0 kb DNA fragment containing partial glpF and glycerol kinase (glpK) genes was amplified by PCR (Mullis and Faloona, Methods Enzymol. 155, 335 (1987)) from FM5 genomic DNA using primers SEQ ID NO:2 and SEQ ID NO:3. A 1.1 kb DNA
15 fragment containing partial glpK and glpX genes was amplified by PCR from
FM5 genomic DNA using primers SEQ ID NO:4 and SEQ ID NO:5. A Muni site was incorporated into primer SEQ ID NO:4. The 5' end of primer SEQ ID NO:4 was the reverse complement of primer SEQ ID NO:3 to enable subsequent overlap extension PCR. The gene splicing by overlap extension technique (Horton et al.,
20 BioTechniques 8, 528 (1990)) was used to generate a 2.1 kb fragment by PCR using the above two PCR fragments as templates anu prim ers SEQ ID NO:2 and SEQ ID NO:5. This fragment represented a deletion of 0.8 kb from the central region of the 1.5 kb glpK gene. Overall, this fragment had 1.0 kb and 1.1 kb flanking regions on either side of the Muni cloning site (within the partial glpK) to
25 allow for chromosomal gene replacement by homologous recombination. The above 2.1 kb PCR fragment was blunt-ended (using mung bean nuclease) and cloned into the pCR-Blunt vector using the Zero Blunt PCR Cloning Kit (Invitrogen, San Diego, CA) to yield the 5.6 kb plasmid pRNlOO containing karamycin and Zeocin resistance genes. The 1.2 kb Hindi fragment
30 from pLoxCatl (unpublished results), containing a chloramphenicol-resistance
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gene flanked by bacteriophage PI IoxP sites (Snaith et al., Gene 166,173 (1995)), was used to interrupt the glpK fragment in plasmid pRNlOO by ligating it to
Munldkested (and blunt-ended) plasmid pKNIOO to yield the 6.9 kb plasmid
pRN101-l. A 376 bp fragment containing the R6K origin was amplified by PCR
5 from the vector pGP704 (Miller and Mekalanos, J. Bacteriol. 170,2575-25 83 (1988)) using primers SEQ ID NO:6 and SEQ ID NO:7, blunt-ended, and ligated to the 5.3 kbAspllS-Aatll fragment (which was blunt-ended) from pRN101-l to yield the 5.7 kb plasmid pRN102-l containing kanamycin and chloramphenicol resistance genes. Substitution of the ColEl origin region in pRN101-l with the
10 R6K origin to generate pRN 102-1 also involved deletion of most of the Zeocin resistance gene. The host for pRN102-l replication was E. coli SY327 (Miller and Mekalanos, J. Bacteriol. 170,2575-2583 (1988)) which contains thepir gene necessary for the function of the R6K origin. Engineering of glycerol kinase mutant RJFl0m with chloramphenicol resistance
15 gene interrupt:
E.coli FM5 was electrotransformed with the non-replicative integration plasmid pRN 102-1 and transformants that were chloramphenicol-resistant (12.5 μg/mL) and kanamycin-sensitive (30 μg/mL) were further screened for glycerol non-utilization on M9 minimal medium containing 1 mM glycerol. An
20 EcoRI digest of genomic DNA from one such mutant, RJFl 0m, when probed with the intact glpK gene via Southern analysis (Southern, J. Mol. Biol. 98, 503-517 (1975)) indicated that it was a double-crossover integrant (glpK gene replacement) since the two expected 7.9 kb and 2.0 kb bands were observed, owing to the presence of an additional EcoRI site within the chloramphenicol resistance gene.
25 The wild-type control yielded the single expected 9.4 kb band. A 13C NMR analysis of mutant RJFlOm confirmed that it was incapable of converting 13C-labeled glycerol and ATP to glycerol-3-phosphate. This glpK mutant was further analyzed by genomic PCR using primer combinations SEQ ID NO:8 and SEQ ID NO:9, SEQ ID NO: 10 and SEQ ID NO: 11, and SEQ ID NO:8 and SEQ
30 ID NO: 11 which yielded the expected 2.3 kb, 2.4 kb, and 4.0 kb PCR fragments respectively. The wild-type control yielded the expected 3.5 kb band with primers SEQ ID NO:8 and SEQ ID NO:l 1. The glpK mutant RJFlOm was electrotransformed with plasmid pAH48 to allow glycerol production from glucose. The glpK mutant E. coli RJFlOm has been deposited with ATCC under
35 the terms of the Budapest Treaty on 24 November 1997.
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Engineering of glycerol kinase mutant RJF10 with chloramphenicol resistance gene interrupt removed:
After overnight growth on YENB medium (0.75% yeast extract, 0.8%
nutrient broth) at 37 °C, E. coli RJFlOm in a water suspension was
5 electrotransformed with plasmid pJW 168 (unpublished results), which contained the bacteriophage PI Cre recombinase gene under the control of the IPTG-inducible lac\JV5 promoter, a temperature-sensitive pSClOl replicon, and an ampicillin resistance gene. Upon outgrowth in SOC medium at 30 °C, transformants were selected at 30 °C (permissive temperature for pJW168
10 replication) on LB agar medium supplemented with carbenicillin (50 ng/mL) and IPTG (1 mM). Two serial overnight transfers of pooled colonies were carried out at 30 °C on fresh LB agar medium supplemented with carbenicillin and IPTG in order to allow excision of the chromosomal chloramphenicol resistance gene via recombination at the loxP sites mediated by the Cre recombinase (Hoess and
15 Abremski, J. Mol. Biol. 181, 351-362 (1985)). Resultant colonies were replica-plated on to LB agar medium supplemented with carbenicillin and IPTG and LB agar supplemented with chloramphenicol (12.5 μg/mL) to identify colonies that were carbenicillin-resistant and chloramphenicol-sensitive indicating marker gene removal. An overnight 30 °C culture of one such colony was used to inoculate
20 10 mL of LB medium. Upon growth at 30 °C to OD (600 nm) of 0.6 AU, the culture was incubated at 37 °C overnight. Several dilutions were plated on prewarmed LB agar medium and the plates incubated overnight at 42 °C (the non-permissive temperature for pJW168 replication). Resultant colonies were replica-plated on to LB agar medium and LB agar medium supplemented with
25 carbenicillin (75 μg/mL) to identify colonies that were carbenicillin-sensitive indicating loss of plasmid pJWl 68. One such glpK mutant, RJFIO, was further analyzed by genomic PCR using primers SEQ ID NO:8 and SEQ ID NO:l 1 and yielded the expected 3.0 kb band confirming marker gene excision. Glycerol non-utilization by mutant RJF10 was confirmed by lack of growth on M9 minimal
30 medium containing 1 mM glycerol. The glpK mutant RJF10 was
electrotransformed with plasmid pAH48 to allow glycerol production from glucose.
EXAMPLE 3
CONSTRUCTION OF E. COLI STRAIN WITH gldA GENE KNOCKOUT
35 The gldA gene was isolated from E. coli by PCR (K. B. Mullis and F. A.
Faloona, Meth. Enzymol. 155,335-350 (1987)) using primers SEQ ID NO: 12 and SEQ ID NO: 13, which incorporate terminal Sphl and Xbal sites, respectively,
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and cloned (T. Maniatis (1982) Molecular Cloning: A Laboratory Manual. Cold Spring Harbor, Cold Spring Harbor, NY) between the Sphl and Xbal sites in pUCl8, to generate pKP8. pKP8 was cut at the unique Sail and Ncol sites within the gldA gene, the ends flushed with Klenow and religated, resulting in a 109 bp 5 deletion in the middle of gldA and regeneration of a unique Sail site, to generate pKP9. A 1.4 kb DNA fragment containing the gene conferring kanamycin resistance (kan), and including about 400 bps of DNA upstream of the translational start codon and about 100 bps of DNA downstream of the translational stop codon, was isolated from pET-28a(+) (Novagen, Madison, Wis)
10 by PCR using primers SEQ ID NO: 14 and SEQ ID NO: 15, which incorporate terminal Sail sites, and subcloned into the unique Sail site of pKP9, to generate pKP13. A 2.1 kb DNA fragment beginning 204 bps downstream of the gldA translational start codon and ending 178 bps upstream of the gldA translational stop codon, and containing the kan insertion, was isolated from pKP13 by PCR
15 using primers SEQ ID NO: 16 and SEQ ID NO: 17, which incorporate terminal Sphl and Xbal sites, respectively, was subcloned between the Sphl and Xbal sites in pMAK705 (Genencor International, Palo Alto, CA), to generate pMP33. E. coli FM5 was transformed with pMP33 and selected on 20 ng/mL kan at 30 °C, which is the permissive temperature for pMAK705 replication. One colony was
20 expanded overnight at 30 °C in liquid media supplemented with 20 p,g/mL kan. Approximately 32,000 cells were plated on 20 \xgfmL kan and incubated for 16 h at 44 °C, which is the restrictive temperature for pMAK705 replication, Transformants growing at 44 °C have plasmid integrated into the chromosome, occurring at a frequency of approximately 0.0001. PCR and Southern blot (E.M.
25 Southern, J. Mol. Biol. 98, 503-517 (1975)) analyses were Used to determine the nature of the chromosomal integration events in the transformants. Western blot analysis (Towbin et al., Proc. Natl. Acad. Sci. 76,4350 (1979)) was used to determine whether glycerol dehydrogenase protein, the product of gldA, is produced in the transformants. An activity assay was used to determine whether
30 glycerol dehydrogenase activity remained in the transformants. Activity in glycerol dehydrogenase bands on native gels was determined by coupling the conversion of glycerol plus NAD+ to dihydroxyacetone plus NADH to the conversion of a tetrazolium dye, MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] to a deeply colored formazan, with phenazine
35 methosulfate as mediator. Glycerol dehydrogenase also requires the presence of 30 mM ammonium sulfate and 100 mM Tris, pH 9 (Tang et al., J. Bacteriol. 140, 182 (1997)). Of 8 transformants analyzed, 6 were determined to be gldA
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knockouts. E. coli MSP33.6 has been deposited with ATCC under the terms of the Budapest Treaty on 24 November 1997.
EXAMPLE 4
CONSTRUCTION OF AN E. COLI STRAIN
5 WITH eloK AND eldA GENE KNOCKOUTS
A 1.6 kb DNA fragment containing the gldA gene and including 228 bps of DNA upstream of the translational start codon and 220 bps of DNA downstream of the translational stop codon was isolated from E. coli by PCR using primers SEQ ID NO: 18 and SEQ ID NO: 19, which incorporate terminal
10 Sphl and Xbal sites, respectively, and cloned between the Sphl and Xbal sites of pUC18, to generate pQN2. pQN2 was cut at the unique Sail and Ncol sites within the gldA gene, the ends flushed with Klenow and religated, resulting in a 109 bps deletion in the middle of gldA and regeneration of a unique Sail site, to generate pQN4. A 1.2 kb DNA fragment containing the gene conferring
15 kanamycin resistance (kan), and flanked by loxP sites was isolated from
pLoxKan2 (Genencor International, Palo Alto, CA) as a Stul/Xhol fragment, the ends flushed with Klenow, and subcloned into pQN4 at the Sail site after flushing with Klenow, to generate pQN8. A 0.4 kb DNA fragment containing the R6K origin of replication was isolated from pGP704 (Miller and Mekalanos,
20 J. Bacteriol. 170, 2575-2583 (1988)) by PCR using primers SEQ ID NO:20 and SEQ ID NO:21, which incorporate terminal Sphl and Xbal sites, respectively, and ligated to the 2.8 kb Sphl/Xbal DNA fragment containing the gldA::kan cassette from pQN8, to generate pKP22. A 1.0 kb DNA fragment containing the gene conferring chloramphenicol resistance (cam), and flanked by loxP sites was
25 isolated from pLoxCat2 (Genencor International, Palo Alto, CA) as an Xbal
fragment, and subcloned into pKP22 at the Xbal site, to generate pKP23. E. col strain RJF10 (see Example 2), which is glpK-, was transformed with pKP23 and transformants with the phenotype kanRcamS were isolated, indicating double crossover integration, which was confirmed by southern blot analysis. Glycerol
30 dehydrogenase gel activity assays (as described in Example 3) demonstrated thai active glycerol dehydrogenase was not present in these transformants. The kan marker was removed from the chromosome using the Cre-producing plasmid pJW168, as described in Example 2, to produce strain KLP23. Several isolates
with the phenotype kanS demonstrated no glycerol dehydrogenase activity, and
35 southern blot analysis confirmed loss of the kan marker.
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EXAMPLE 5
PLASMID CONSTRUCTION AND STRAIN CONSTRUCTION FOR THE EXPRESSION OF GLYCEROL 3-PHOSPHATE DEHYDROGENASE (DAR1) AND/OR GLYCEROL 3-PHOSPHATASE CGPP2)
5 Construction of expression cassettes for glycerol 3-phosphatase (gpp2): The Saccharomyces cerevisiae chromosomeV lamda clone 6592 (GenBank, accession # U18813xl 1) was obtained from ATCC. The glycerol 3-phosphate phosphatase gene (GPP2) was cloned by cloning from the lamda clone as target DNA using synthetic primers (SEQ ID NO:22 with SEQ ID
10 NO:23) incorporating an BamHI-RBS-Xbal site at the 51 end and a Smal site at the 3' end. The product was subcloned into pCR-Script (Stratagene, Madison, WI) at the Srfl site to generate the plasmid pAH15 containing GPP2. The plasmid pAH15 contains the GPP2 gene in the inactive orientation for expression from the lac promoter in pCR-Script SK+. The BamHI-Smal fragment from pAH15
15 containing the GPP2 gene was inserted into pBlueScriptll SK+ to generate
plasmid pAH19. The pAH19 contains the GPP2 gene in the correct orientation for expression from the lac promoter. The Xbal-PstI fragment from pAH19 containing the GPP2 gene was inserted into pPHOX2 to create plasmid pAH21. The pAH21/DH5a is the expression plasmid.
20 Construction of expression cassettes for glycerol 3-phosphate dehydrogenase (DAR1):
DAR1 was isolated by PCR cloning from genomic S. cerevisiae DNA using synthetic primers (SEQ ID NO:24 with SEQ ID NO:25). Successful PCR cloning places an Ncol site at the 5' end of DAR1 where the ATG within Ncol is
25 the DAR1 initiator methionine. At the 3' end of DAR1 a BamHI site is introduced following the translation terminator. The PCR fragments were digested with Ncol + BamHI and cloned into the same sites within the expression plasmid pTrc99A (Pharmacia, Piscataway, NJ) to give pDARlA.
In order to create a better ribosome binding site at the 5' end of DARi, an
30 Spel-RBS-NcoI linker obtained by annealing synthetic primers (SEQ ID NO:26 with SEQ ID NO:27) was inserted into the Ncol site of pDARIA to create pAH40. Plasmid pAH40 contains the new RBS and DAR1 gene in the correct orientation for expression from the trc promoter of pTrc99A (Pharmacia, Piscataway, NJ). The NcoI-BamHI fragment from pDARl A and an second set of
35 Spel-RBS-NcoI linker obtained by annealing synthetic primers (SEQ ID NO:28 with SEQ ID NO:29) was inserted into the Spel-BamHI site of pBC-SK+
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(Stratagene, Madison, WI) to create plasmid pAH42. The plasmid pAH42 contains a chloramphenicol resistant gene.
Construction of expression cassettes for darl and gpp2:
Expression cassettes for DARl and GPP2 were assembled from the
5 individual DARl and GPP2 subclones described above using standard molecular biology methods. The BamHI-PstI fragment from pAH19 containing the
ribosomal binding site (RBS) and GPP2 gene was inserted into pAH40 to create
pAH43. The BamHI-PstI fragment from pAH19 containing the RBS and GPP2
gene was inserted into pAH42 to create pAH45.
10 The ribosome binding site at the 5' end of GPP2 was modified as follows.
A BamHI-RBS-Spel linker, obtained by annealing synthetic primers
GATCCAGGAAACAGA (SEQ ID NO:30) with CTAGTCTGTTTCCTG (SEQ
ID NO:31) to the Xbal-PstI fragment from pAH19 containing the GPP2 gene, was
inserted into the BamHI-PstI site of pAH40 to create pAH48. Plasmid pAH48
15 contains the DARl gene, the modified RBS, and the GPP2 gene in the correct
orientation for expression from the trc promoter of pTrc99A (Pharmacia,
Piscataway, NJ).
Transformation of E. coli:
The plasmids described here were transformed into E. coli DH5oc, FM5
20 and KLP23 using standard molecular biology techniques. The transformants were
verified by their DNA RFLP pattern.
EXAMPLE 6
CONSTRUCTION OF EXPRESSION PLASMIDS FOR USE IN
TRANSFORMATION OF ESCHERICHIA COLI WITH GENES FROM THE
25 KLEBSIELLA PNEUMONIAE dha REGULON
Construction of the expression vector pTacIO:
The E. coli expression vector pTacIQ was prepared by inserting laclq gene (Farabaugh, Nature 274(5613), 765-769 (1978)) and tac promoter (Amann et al., Gene 25, 167-178 (1983)) into the restriction endonuclease site EcoRI of pBR322
30 (Sutcliffe, Cold Spring Harb. Symp. Quant. Biol. 43, 77-90 (1979)). A multiple cloning site and terminator sequence (SEQ ID NO:32) replaces the pBR322 sequence from EcoRI to Sphl. Subcloning the glycerol dehydratase genes (dhaBJ-,2,3, X):
The open reading frame for the dhaB3 gene was amplified from pHK28-26
35 by PCR using primers (SEQ ID NO:33 and SEQ ID NO:34) incorporating an EcoRI site at the 5' end and a Xbal site at the 3' end. The product was subcloned
54

into PLitmus29 (New England Biolab, Inc., Beverly, MA) to generate the plasmid pDHAB3 containing dhaB3.
The region containing the entire coding region for dhaBl, dhaB2, dhaB3 and dhaBX of the dhaB operon from pHK28-26 was cloned into pBluescriptIIKS+ (Stratagene, La Jolla, CA) using the restriction enzymes Kpnl and EcoRI to create the plasmid pM7.
The dhaBX gene was removed by digesting plasmid pM7 with Apal and Xbal, purifying the 5.9 kb fragment and ligating it with the 325-bp Apal-Xbal fragment from plasmid pDHAB3 to create pMl 1 containing dhaBl, dhaB2 and
10 dhaB3,
The open reading frame for the dhaBl gene was amplified from pHK28-26 by PCR using primers (SEQ ID NO:35 and SEQ ID NO:36) incorporating a Hindlll site and a consensus ribosome binding site at the 5' end and a Xbal site at the 31 end. The product was subcloned into pLitmus28 (New England Biolab, Inc., Beverly, MA) to generate the plasmid pDTl containing dhaBl.
A Notl-Xbal fragment from pMl 1 containing part of the dhaBl gene, the dhaB2 gene and the dhaB3 gene was inserted into pDTl to create the dhaB expression plasmid, pDT2. The Hindlll-Xbal fragment containing the dhaB(l,2,3) genes from pDT2 was inserted into pTacIQ to create pDT3.
20 Subcloning the U3-propanediol dehydrogenase gene (dhaT):
The KpnI-SacI fragment of pHK28-26, containing the 1,3-propanediol dehydrogenase (dhaT) gene, was subcloned into pBluescriptll KS+ creating plasmid pAHl. The dhaT gene was amplified by PCR from pAHl as template DNA and synthetic primers (SEQ ID NO:37 with SEQ ID NO:38) incorporating an Xbal site at the 5' end and a BamHI site at \ht 3' end. The product was subcloned into pCR-Script (Stratagene) at the Srfl site to generate the plasmids pAH4 and pAH5 containing dhaT. The plasmid pAH4 contains the dhaT gene in \ the right orientation for expression from the lac promoter in pCR-Script and pAH5
contains dhaT gene in the opposite orientation. The Xbal-BamHI fragment from
30 pAH4 containing the dhaT gene was inserted into pTacIQ to generate plasmid pAH8. The Hindll-BamHI fragment from pAH8 containing the RBS and dhaT gene was inserted into pBluescriptIIKS+ to create pAHl 1.
Construction of an expression cassette for dhaT and dhaBn.2.3):
56

—An expression cassette for dhaTand dhaB(l,2,3) was assembled from the individual dhaB(l,2,3) and dhaT subclones described previously using standard molecular biology methods. A Spel-SacI fragment containing the dhaB(l,2,3) genes from pDT3 was inserted into pAHl 1 at the Spel-SacI sites to create pAH24. A Sall-Xbal linker (SEQ ID NO:39 and SEQ ID NO:40) was inserted into pAH5 that was digested with the restriction enzymes Sall-Xbal to create pDT16. The linker destroys the Xbal site. The 1 kb Sall-Mlul fragment from pDT16 was then inserted into pAH24 replacing the existing Sall-Mlul fragment to create pDT18. pDT21 was constructed by inserting the Sall-NotI fragment from pDT18 and the Notl-Xbal fragment from pM7 into pCL1290 (SEQ ID NO:41). The glucose isomerase promoter sequence from Streptomyces (SEQ ID NO:42) was cloned by PCR and inserted into EcoRI-HinDIII sites of pLitmus28 to construct pDT5. pCL1925 was constructed by inserting EcoRI-PvuII fragment of pDT5 into the EcoRI-PvuII site of pCL1920. pDT24 was constructed by cloning the HinDIII-MluII fragment of pDT21 and the Mlul-Xbal fragment of pDT21 into the HinDIII-Xbal sites of PCL1925.--
Construction of an expression cassette for dhaT and dhaB(l,2.3,X):
pDT21 was constructed by inserting the Sall-NotI fragment from pDT18 151 and the Notl-Xbal fragment from pM7 into pCL1920 (SEQ ID NO:41), The
glucose isomerase promoter sequence from Streptomyces (SEQ ID NO:42) was
cloned by PCR and inserted into EcoRI-HinDIII sites of pLitmus28 to construct
pDT5. pCL1925 was constructed by inserting EcoRI-PvuII fragment of pDT5
into the EcoRI-PvuI site of pCL1920. pDT24 was constructed by cloning the
20 HinDIII-MluII fragment of pDT21 and the Mlul-Xbal fragment of pDT21 into the
HinDIII-Xbal sites of pCL1925.
Construction of an expression cassette for dhaR, orfY, dhaT, orfX, orfW and
dhaBa.2.3.X):
pDT29 was constructed by inserting the SacI-EcoRI fragment of
pHK28-26 into SacI-EcoRI sites of pCL1925.
Construction of an expression cassette for dhaR, orfY, orfX, orffV and
dhaB(L2S,X):
A derivative of plasmid pDT29 was constructed in which all except the
first 5 and the last 5 codons (plus stop codon) of the gene dhaTwere deleted by a 301 technique known as PCR-mediated overlap extension. Using pDT29 as template,
2 primary PCR products were generated using the following primers: •
SEQ ID NO:43 = 5'GAC GCA ACA GTA TTC CGT CGC3';
SEQ ID NO:44 = 5'ATG AGC TAT CGT ATG TTC CGC CAG GCA TTC TGA
GTGTTAACG3';
SEQ ID NO:45 = 5'GCC TGG CGG AAC ATA CGA TAG CTC ATA ATA
TAC3';
SEQ ID NO:46 = 5'CGG GGC GCT GGG CCA GTA CTG3'.

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SEQ ID NO:45 was paired with SEQ ID NO:46 to generate a product of 931 bps and encompassing nucleic acid including 51 dhaBl (to unique Seal site), all of orfY, and the first five codons of dhaT. SEQ ID NO:43 was paired with SEQ ID NO:44 to generate a product of 1348 bps and encompassing nucleic acid
5 including the last five codons (plus stop codon) of dhaT, all of orfiC, all of orffV, and 5' dhaR (to unique Sapl site). The 15 bases at the 5' end of SEQ ID NO:44 constitute a tail that is the inverse complement of a 15 base portion of SEQ ID NO:45. Similarly, the 11 bases at the 5' end of SEQ ID NO:45 constitute a tail that is the inverse complement of an 11 base portion of SEQ ID NO:44. Thus, the
10 2 primary PCR products were joined together after annealing (via 26 bp tail overlap) and extending by PCR, to generate a third nucleic acid product of 2253 bps. This third PCR product was digested with Sapl and Seal and ligated into pDT29 which was also digested with Sapl and Seal, to generate the plasmid pKP32, which is identical to pDT29, except for the large, in-frame deletion within
15 dhaT.
EXAMPLE 7
CONVERSION OF GLUCOSE TO 1,3-PROPANEDIOL USING
E. COLI STRAIN KLP23/pAH48/pDT29 AND
THE IMPROVED PROCESS USING KLP23/DAH48/DKP32
20 Pre-Culture:
KLP23/pAH48/pDT29 and KLP23/pAH48/pKP32 were pre-cultured for seeding a fermenter in 2YT medium (10 g/L yeast extract, 16 g/L tryptone, and 10 g/L NaCl) containing 200 mg/L carbenicillin (or ampicillin) and 50 mg/L spectinomycin. KLP23/pAH48/pKP32 is identical to KLP23/pAH48/pDT29
25 except that dhaT is deleted.
Cultures were started from frozen stocks (10% DMSO as cryoprotectant) in 500 mL of medium in a 2-L Erlenmeyer flask, grown at 35 °C in a shaker at 250 rpm until an OD550 of approximately 1.0 AU was reached and used to seed the fermenter.
30 Fermenter medium:
The following components were sterilized together in the fermenter vessel 45 g KH2P04,12 g citric acid, 12 g MgS04-7H20, 30 g yeast extract, 2.0 g ferric ammonium citrate, 5 mL Mazu DF204 as antifoam, 1.2 g CaCl2-2H20, and 7.3 mL sulfuric acid. The pH was raised to 6.8 with 20-28% NH4OH and the
35 following components were added: 1.2 g carbenicillin or ampicillin, 0.30 g spectinomycin, 60 mL of a solution of trace elements and glucose (from a 60-67 weight % feed). After inoculation, the volume was 6.0 L and the glucose
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concentration was 10 g/L. The solution of trace elements contained (g/L): citric acid. H20 (4.0), MnS04-H20 (3.0), NaCl (1.0), FeS04-7H20 (0.10), CoCl2-6H20 (0.10), ZnS04-7H20 (0.10), Cu_S04-5H20 (0.010), H3B03 (0.010), and
Na2Mo04-2H20 (0.010).
5 Fermentation growth:
A 15 L stirred tank fermenter was prepared with the medium described above. The temperature was controlled at 35 °C and aqueous ammonia (20-28 weight %) was used to control pH at 6.8. Initial values for air flow rate (set to minimum values of between 6 and 12 standard liters per min) and agitator
10 speed (set to minimum values of between 350 and 690 rpm) were set so that dissolved oxygen (DO) control was initiated when OUR values reached
approximately 140 mmol/L/h. Back pressure was controlled at 0.5 bar. DO control was set at 10%. Except for minor excursions, glucose was maintained at between 0 g/L and 10 g/L with a 60% or 67% (wt) feed. Vitamin B12 or
15 coenzyme B 12 was added as noted below.
16 Fermentation with KLP23/PAH48/DDT29:
A representative fermentation summary of the conversion of glucose to 1,3-propanediol (1,3-PD) using E. coli strain KLP23/pAH48/pDT29 is given in Table 4. Vitamin B12 (0.075 g/L, 500 mL) was fed, starting 3 h after inoculation,
20 at a rate of 16 mL/h. The yield of 1,3-propanediol was 24 wt % (g
1,3-propanediol/g glucose consumed) and a titer of 68 g/L 1,3-propanediol was obtained.
TABLE 4
Representative fermentation summary of the conversion of glucose to 1,3-propanediol (1,3-PD) using E. coli strain KLP23/pAH48/pDT29
Time (h) OD550 (AU) DO (%) Glucose (g/L) Glycerol (g/L) 1,3-PD (g/I

0 0 150 12.9 0.0 0
6 17 80 8.3 3.i i
12 42 53 2.8 12.5 9
18 98 9 5.7 12.6 32
24 136 11 32.8 12.0 51
30 148 10 12.3 13.3 62
32 152 11 12.5 14.3 65
38 159 11 1.5 17.2 68
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Similar results were obtained with an identical vitamin B12 feed at twice the concentration or bolus additions of vitamin B12 across the time course of the
fermentation. The highest titer obtained Was 77 g/L.
Improved fermentation with KLP23/PAH48/PKP32:
5 A representative fermentation summary of the conversion of glucose to
1,3-propanediol (1,3-PD) using E. coli strain KLP23/pAH48/pKP32 is given in Table 5. Vitamin B12 (0.150 g/L, 500 mL) was fed, starting 3 h after inoculation, at a rate of 16 mL/h. After 36 h, approximately 2 L of fermentation broth was purged in order to allow for the continued addition of glucose feed. The yield of
10 1,3-propanediol was 26 wt % (g 1,3-propanediol/g glucose consumed) and a titer of 112 g/L 1,3-propanediol was obtained.
TABLE 5
Representative fermentation summary of the improved conversion of glucose to
1,3-propanediol (1,3-PD) using E. coli strain KLP23/pAH48/pKP32
Time(h) OD550(AU) DO (%) Glucose (g/L) Glycerol (g/L) 1,3-PD (g/L)

0 0 148 12.8 0.0 0
6 22 84 6.9 3.3 0
12 34 90 9.7 10.4 7
18 66 43 9.3 5.9 24
24 161 9 0.2 2.5 46
30 200 10 0.2 6.0 67
36 212 10 1.2 9.7 88
42 202 2 0.1 15.5 98
48 197 12 1.2 23.8 112
Similar results were obtained with an identical vitamin B12 feed at half the
15 concentration or bolus additions of vitamin B \ 2 across the time course of the fermentation. The highest titer obtained was 114 g/L.
EXAMPLE 8
ENGINEERING OF TRIOSEPHOSPHATEISOMERASE MUTANT OF
E. COLI KLP23 FOR ENHANCED YIELD OF
20 1.3-PROPANEDIOL FROM GLUCOSE
Construction of plasmid for triosephosphate isomerase gene replacement in E. coli KLP23:
E. coli KLP23 genomic DNA was prepared using the Puregene DNA Isolation Kit (Gentra Systems, Minneapolis, .MN).. A 1.0 kb DNA fragment
25 containing cdh and the 3' end of triosephosphate isomerase (tpiA) genes was
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amplified by PCR (Mullis and Faloona, Methods Enzymol. 155,335-350 (1987)) from KLP23 genomic DNA using primers SEQ ID NO:47 and SEQ ID NO:48. A
1.0 kb DNA fragment containing the 5' end of tpUjiiQ, and the 5' end of yilR
genes was amplified by PCR from KLP23 genomic DNA using primers SEQ ID
5 NO:49 and SEQ ID NO:50. A Seal site was incorporated into primer SEQ ID NO:49. The 5' end of primer SEQ ID NO:49 was the reverse complement of primer SEQ ID NO:48 to enable subsequent overlap extension PCR. The gene splicing by overlap extension technique (Horton et al., BioTechniques 8, 528-535 (1990)) was used to generate a 2.0 kb fragment by PCR using the above two PCR
10 fragments as templates and primers SEQ ID NO:47 and SEQ ID NO:50. This fragment represented a deletion of 73% of the 768 bp tpiA structural gene. Overall, this fragment had 1.0 kb flanking regions on either side of the Seal cloning site (within the partial tpiA) to allow for chromosomal gene replacement by homologous recombination.
15 The above blunt-ended 2.0 kb PCR fragment was cloned into the
pCR-Blunt vector using the Zero Blunt PCR Cloning Kit (Invitrogen, San Diego, CA) to yield the 5.5 kb plasmid pRN 106-2 containing kanamycin and Zeocin resistance genes. The 1.2 kb Hindi fragment from pLoxCatl (unpublished results), containing a chloramphenicol-resistance gene flanked by bacteriophage
20 PI lox? sites (Snaith et al., Gene 166, 173-174 (1995)), was used to interrupt the tpiA fragment in plasmid pRN 106-2 by ligating it to Sorf-digested plasmid pRN 106-2 to yield the 6.8 kb plasmid pRN 107-1. Engineering of triosephosphate isomerase mutant RJ8m by linear DNA transformation:
2 5 Using pRN 107-1 as template and primers SEQ ID NO :47 and SEQ ID
NO:50, the 3.2 kb fragment containing tpiA flanking regions and the /oxP-CmR-ZoxP cassette was PCR amplified and gel-extracted. E. coli KLP23 was electrotransformed with up to 1 ug of this 3.2 kb linear DNA fragment and transformants that were chloramphenicol-resistant (12.5 ug/mL) and kanamycin-
30 sensitive (30 ug/mL) were further screened on M9 minimal media for poor
glucose utilization on 1 mM glucose, for normal gluconate utilization on 1 mM gluconate, and to ensure the glycerol non-utilization phenotype of host KLP23 on .1 mM glycerol. An £coRI digest of genomic DNA from one such mutant, RJ8m, when probed with the intact tpiA gene via Southern analysis (Southern, J. Mol.
35 Biol. 98, 503-517 (1975)) indicated that it was a double-crossover integrant (tpiA gene replacement) since the two expected 6.6 kb and 3.0 kb bands were observed, owing to the presence of an additional jEcoRI site within the chloramphenicol
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resistance gene. As expected, the host KLP23 and wild-type FM5 controls yielded single 8.9 kb and 9.4 kb bands respectively. This tpiA mutant was further
analyzed by genomic PCR using primers SEQ ID NO:51 and SEQ ID NO:52,
which yielded the expected 4.6 kb PCR fragment while for the same primer pair
5 the host KLP23 and wild-type FM5 strains both yielded the expected 3.9 kb PCR fragment. When cell-free extracts from tpiA mutant RJ8m and host KLP23 were tested for tpiA activity using glyceraldehyde 3-phosphate as substrate, no activity was observed with RJ8m. The tpiA mutant RJ8m was electrotransformed with plasmid pAH48 to allow glycerol production from glucose and also with both
10 plasmids pAH48 and pDT29 or pKP32 to allow 1,3-propanediol production from glucose. The chloramphenicol resistance marker was eliminated from RJ8m to give RJ8.
EXAMPLE 9
CONVERSION OF GLUCOSE TO 1,3-PROPANEDIOL USING E. COLI
15 STRAIN RJ8/pAH48/pDT29 AND THE IMPROVED
PROCESS USING RJ8/PAH48/DKP32 Pre-Culture:
RJ8/pAH48/pDT29 and RJ8/pAH48/pKP32 were pre-cultured for seeding a fermenter as described in Example 7. RJ8/pAH48/pKP32 is identical to
20 RJ8/pAH48/pDT29 except that dhaT is deleted. Fermenter medium:
Fermenter medium was as described in Example 7. Fermentation growth:
Fermenter growth was as described in Example 7 except that initial values
25 for air flow rate (set to minimum values of between 5 and 6 standard liters per min) and agitator speed (set to minimum values of between 300 and 690 rpm) were set so that dissolved oxygen (DO) control was initiated when OUR values reached between 60 and 100 mmol/L/h. Vitamin B12 or coenzyme B12 was added as noted below.
30 Fermentation with RJ8/pAH48/pDT29:
A representative fermentation summary of the conversion of glucose to 1,3-propanediol (1,3-PD) using E. coli strain RJ8/pAH48/pDT29 is given in Table 6. Vitamin B12 was provided as bolus additions of 2,16 and 16 mg at 2, 8, and 26 h, respectively. The yield of 1,3-propanediol was 35 wt % (g
3 5 1,3-propanediol/g glucose consumed) and a titer of 50.1 g/L 1,3-propanediol was obtained.
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TABLE 6
Representative fermentation summary of the conversion of glucose to
1,3-propanediol (1,3-PD) using R coli strain RJ8/pAH48/pDT29'
TimeQi) OD550 (AU) DO (%) "Glucose (g/L) Glycerol (g/L) 1,3-PD (g/L)

0 0 140 10.6 0.1 0.0
6 5 107 11.1 0.5 0.4
10 16 90 8.5 1.7 1.3
14 25 86 1.8 2.4 5.9
19 38 53 3.5 5.9 15.4
25 53 38 0.1 9.2 26.7
31 54 10 4.5 7.4 39.0
37 37 23 17.2 6.0 45.0
43 21 13 9.9 7.7 50.1
Improved fermentation with RJ8/pAH48/pKP32:
A representative fermentation summary of the conversion of glucose to 1,3-propanediol (1,3-PD) using E. coli strain RJ8/pAH48/pKP32 is given in
5 Table 7. Vitamin B^ was provided as bolus additions of 48 and 16 mg at approximately 26 and 44 hr, respectively. The yield of 1,3-propanediol was 34 wt % (g 1,3-propanediol/g glucose consumed) and a titer of 129 g/L 1,3-propanediol was obtained.
TABLE 7
Representative fermentation summary of the improved conversion of glucose
to 1,3-propanediol (1,3-PD) using E. coli strain RJ8/pAH48/pKP32.
Time(h) OD550 (AU) DQ(%) Glucose (g/L) Glycerol (g/L) 1,3-PD (g/L)

0 0 150 12.6 0.1 0
6 12 113 6.0 2.6 0
12 24 99 0.0 10.6 0
18 51 76 2.4 28.9 0
24 78 82 2.4 44.2 5
30 114 70 3.8 26.9 33
36 111 72 0.0 20.0 57
42 139 65 0.1 21.9 69
48 157 36 0.1 - 22.4 79
55 158 25 0.2 21.4 94
64 169 14 0.1 15.8 113
72 169 12 0.1 13.4 119
74 162 14 0.1 14.8 129
10
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EXAMPLE 10
IDENTIFICATION OF THE E. COLI NON-SPECIFIC CATALYTIC
ACTIVITY (vahD) IN THE IMPROVED 1.3-PROPANEDIOL PROCESS Demonstration of non-specific catalytic activity in 1.3-propanediol-producing
5 fermentations with the improved catalyst:
A whole cell assay for 1,3-propanediol dehydrogenase activity was used to demonstrate that the non-specific catalytic activity in E. coli is present under fermentative conditions after the addition of vitamin B12 and the production of 3-hydroxypropionaldehyde (3-HPA), but not before. A recombinant E. coli strain
10 containing the glycerol-production and 1,3-propanediol-production plasmids, pAH48 and pKP32, respectively, was grown in 10 L fermenters, essentially as described in Example 7, but in the absence of vitamin B12. A vitamin B12 bolus (48 mg) was added when the tanks reached approximately 100 OD550. Aliquots of cells were taken from the tanks immediately before and 2 h post-vitamin B12
15 addition. The cells were recovered by centrifugation and resuspended to their original volume in PBS buffer containing 150 μg/mL chloramphenicol to inhibit new protein synthesis. An appropriate volume of the chloramphenicol treated cells was added to 250 mL baffled flasks containing a reaction mixture (PBS buffer containing 10 g/L glucose, 10 g/L glycerol, 1 mg/L coenzyme B12, and 150
20 μg/mL chloramphenicol) so that the final volume was 50 mL at an OD550 of
approximately 10. The flasks, protected from light, were shaken at 250 rpm at 35 °C. Aliquots for HPLC analysis were taken over time. Time-dependent production of 3-HPA was observed in flasks containing cells recovered from the fermenter either pre- or post-vitamin B12 addition. In direct contrast, significant
25 levels of 1,3-propanediol were observed only in those flasks containing cells recovered from the fermenter post-vitamin B12 addition. Detection of non-specific catalytic activity in cell-free extracts:
A native gel activity stain assay was used to demonstrate non-specific catalytic activity in cell-free extracts. Cells were recovered, pre- and post-vitamin
30 B12 addition, from representative 10-L fermentations employing recombinant
E. coli strains containing the glycerol-production and 1,3-propanediol-production plasmids, pAH48 and pKP32, respectively; and cell-free extracts were prepared by cell disruption using a French press. The cell-free extracts, a preparation of pure
Klebsiella pneumoniae 1,3-propanediol dehydrogenase (dhaT), and molecular
3 5 weight standards were applied to and run out on native gradient polyacrylamide gels. The gels were then exposed to either the substrates 1,3-propanediol and NAD+ or ethanol and NAD+. As expected in the gels where 1,3-propanediol was
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the substrate, an activity stain for DhaT was observed which migrated on the native gel at approximately 340 Kdal. This activity was observed only in lanes
where pure. Klebsiella pneumoniae 1,3 -propanediol dehydrogenase was applied. In contrast, "where 1,3-propanediol was the substrate and post-vitamin B12 cell-
5 free extracts were applied, a non-specific catalytic activity was observed at
approximately 90 Kdal. When ethanol was used as a substrate, neither the DhaT band nor the non-specific catalytic activity band were visible, but a separate band was found pre- and post-vitamin B12 addition at approximately 120 Kdal. This new band most likely represents an alcohol dehydrogenase with specificity
10 towards ethanol as substrate as is typically found in all organisms.
This native gel assay, where proteins are separated by molecular weight
prior to the enzymatic assay step, offered greater sensitivity and accuracy in
measuring the reduction of 1,3-propanediol in those constructs with low activity and where the activity is likely to be distinct from the alcohol dehydrogenases
15 with specificity towards ethanol as substrate that have been well characterized for E. coli and found in all organisms. The dehydrogenase assay works on the principle that dehydrogenase catalyzes the transfer of electrons from 1,3-propanediol (or other alcohols) to NAD+. PMS (phenazine methosulfate) then couples electron transfer between NADH and a tetrazolium bromide dye (MTT, 3-
20 [4,5-dimethylthiazol-2-y}]-2,5-diphenyltetrazoIium bromide) which forms a
precipitate in the gel. After a few hours to overnight soaking in the substrates, the gels are washed to remove reagents and soluble dye. At bands on the gel where there is an active dehydrogenase, an insoluble blue dye forms. Various aspects of the assay have been described by Johnson and Lin (J. Bacteriol 169:2050 (1987)).
25 Purification and identification of the non-specific catalytic activity in E. coli: A large scale, partial purification of non-specific catalytic activity was performed on cells harvested from the end of a typical 1,3-propanediol production run as described in the improved process using KLP23/pAH48/pKP32 of Example 7. The cell pellet (16 g) was washed and resuspended three times in 20 mL of 50
30 mM Hepes buffer, pH 7.5. The cells in the suspension were lysed by sonication. The cell-free extract was obtained by centrifugation (15 min, 20,000 x g, 10 °C) and the supernatant was further clarified by addition of 250 mg of protamine sulfate with stirring on ice. The supernatant obtained by centrifugation (20 min,
20,000 x g, 10 °C) was fractionated by passage through a Superdex® 200
35 preparative grade column (6 x 60 cm) equilibrated with Hepes buffer. Fractions of 10 mL each were collected and an aliquot of each was concentrated twentyfive-fold using 10,000 MW cutoff Centricon® membranes prior to assay by the native
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gel activity stain. The non-specific catalytic activity was identified in fractions 107-112, and the peak activity in fractions 108-109. A larger aliquot (7 mL each)
effractions 108 and 109 were concentrated fifty-fold and loaded on all lanes of a 12-lane native gel. The gel was cut in half and one half was stained for
5 dehydrogenase activity where a dark blue band appeared that represented the nonspecific catalytic activity. The unstained gel was aligned top to bottom with the stained gel and a band was cut on the unstained gel that corresponded to the band of non-specific catalytic activity. The gel strip was pulverized and soluble protein was extracted by immersing the pulverized particles in 0.5 mL of 2D-loading
10 buffer, heating to 95 °C for 5 min, and centrifugation to remove the gel particles. The supernatant was loaded onto an isoelectricfocusing (IEF) strip for 2-dimension polyacrylamide gel electrophoresis (2D-PAGE) using conditions described for 2D-PAGE of E. coli extracts in the Swiss 2D database (http://www.expasy.ch/ch2d/; Tonella et al. Electrophoresis 19:1960-1971
15 (1998)). The gel was transferred to a PVDF membrane by electroblotting. The membrane was stained for proteins using the Colloidal blue gel stain. The stained blot used to obtain the identity of the non-specific catalytic activity is shown in Figure 6. Spots were identified using standard techniques for amino terminus peptide sequencing. Only a single spot (Spot A) encoded for an oxidoreductase
20 activity. Nineteen cycles of Spot A (Figure 6) yielded a 100% identity match by the FASTA search tool with the amino-terminus of yqhD, an E. coli open reading frame with putative oxidoreductase activity. Complete amino acid sequence for the protein encoded by yqhD is given in SEQ ID NO:57; the corresponding DNA sequence is given in SED ID NO:58. The yqhD gene has 40% identity to the gene
25 adhB in Clostridium, a probable NADH-dependent butanol dehydrogenase 2. Gene Disruption of yqhD in E. coli KLP23:
Biochemical assays and amino-terminal amino acid sequencing suggested that non-specific catalytic activity may be encoded by the E. coli yqhD gene. This
gene of unknown function encodes a hypothetical oxidoreductase and contains
30 two alcohol dehydrogenase signatures also found in the Citrobacter freundii and Klebsiella pneumoniae 1,3-propanediol dehydrogenase encoded by the dhaT gene.
To disrupt this gene, yqhD and 830 bp of 5'-flanking DNA sequence and 906 bp of 3'-flanking DNA sequence were amplified from E. coli KLP23 (Example 4) genomic DNA in a PCR using Taq polymerase and the following
35 primers:
(SEQ ID NO:59) S'-GCGGTACCGTTGCTCGACGCTCAGGTTTTCGG-S' (SEQ IDNOrbO) 5’-GCGAGCTCGACGCTTGCCCTGATGATCGAGTTTTGC-3’
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The reaction was run at 94 °C for 1 min, 50 °C for 1 min, and 72 °C for 3 min for 35 cycles followed by a final extension at 72 °C for 5 min. The resulting 3.7 Kb
DNA fragment was purified, digested with Sad and Kpnl and ligated to similarly
digested pBluescriptll KS(+) (Strategene) for 16 h at 16 °C. The ligated DNA
5 was used to transform E. coli DH5α (Gibco/BRL) and the expected plasmid, pJSP29, was isolated from a transformant demonstrating white colony color on LB agar (Difco) containing X-gal (40 μg/mL) and ampicillin (100 μg/mL). Plasmid pJSP29 was digested with Aflll and Ndel to liberate a 409 bp DNA fragment comprising 363 bp of the yqhD gene and 46 bp of 3'-flanking DNA
10 sequence. The remaining 5,350 bp DNA fragment was purified and ligated to the 1,374 bp AflHINdel DNA fragment containing the kanamycin resistance gene from pLoxKan2 (Genencor International, Palo Alto, CA) for 16 h at 16 °C. The ligated DNA was used to transform E. coli DH5a and the expected plasmid, pJSP32-Blue, was isolated from a transformant selected on LB agar media
15 containing kanamycin (50 μg/mL). Plasmid pJSP32-Blue was digested with Kpnl and Sad and the 3,865 bp yqhD disruption cassette was purified and ligated to similarly digested pGP704 (Miller and Mekalanos, J. Bacteriol. 170:2575-2583 (1988)) for 16 h at 16 °C. The ligated DNA was usH tn transform E. coli SY327 (Miller and Mekalanos, J. Bacteriol. 170:2575-258: 18)) and the expected
20 plasmid, pJSP32, was isolated from a transformant: ed on LB agar media containing kanamycin (50 μg/mL). Plasmid pJSP3; transformed into E. coli KLP23 and transformants were selected on LB agar containing kanamycin (50 μg/mL). Of the 200 kanamycin-resistant transformants screened, two demonstrated the ampicillin-sensitive phenotype expected for a double-crossover
25 recombination event resulting in replacement of the yqhD gene with the yqhD disruption cassette.
The disruption of the yqhD gene was confirmed by PCR using genomic DNA isolated from these two transformants as the template and the following set! of primer pairs:
30 Set#l:
(SEQ IDNO:61) S'-GCGAGCTCGACGCTTGCCCTGATCGAGTTTTGC-S'
(SEQ ID NO:62) S'-CAGCTGGCAATTCCGGTTCGO'
Set #2:
(SEQ ID NO:63) S'-CCCAGCTGGCAATTCCGGTTCGCTTGCTGTO'
35 (SEQ ID NO:64) 5'-GGCGACCCGACGCTCCAGACGGAAGCTGGT-3' Set#3: (SEQ ID NO:65) 5'-CCGCAAGATrCACGGATG€ATCGTGAAGGG-3'
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(SEQ ID NO:66) 5'-CGCCTTCnGACGAGTTCTGAGCGGGA-3' Set #4:
(SEQ ID NO:67) S'-GGAATTCATGAACAACTTTAATCTGCACACO' (SEQ ID NO:68) S'-GmGAGGCGTAAAAAGCTTAGCGGGCGGC-S'
5 The reactions were run using either Expand High Fidelity Polymerase (Boehringer Manheim) or Platinum PCR Supermix containing Taq polymerase (Gibco/BRL) at 94 °C for 1 min, 50 °C for 1 min, and 72 °C for 2 min for 35 cycles followed by a final extension at 72 °C for 5 min. The resulting PCR products were analyzed by gel electrophoresis in 1.0 % (w/v) agarose. The results summarized in Table 8
10 confirmed disruption of the yqhD gene in both transformants.
TABLE 8

Primer Set Expected Size (bp) Observed Size (bp)
yqhD disruption yqhD wild-type
1 1,200 no product -1,200
2 1,266 no product -1,266
3 2,594 no product -2,594
4 no product 1,189 -900
The yqhD disruption deletes the 3' end of yqhD, including 46 bp of 3'-flanking
intergenic DNA sequence. The deletion removes 363 bp of 2'yqhD coding 15 sequence corresponding to 121 amino acids. A stop codon is present 15 bp
downstream of the remaining yqhD coding sequence in the kanamycin resistance
cassette.
Plasmids pAH48 and pKP32 were co-transformed into E. coli KLP23
(yqhD-) and transformants containing both plasmids were selected on LB agar
20 containing ampicillin (100 μg/mL) and spectinomycin (50 μg/mL). A
representative transformant was tested for its ability to covert glucose to 1,3-propanediol in 10 L fermentations either in the presence or absence of vitamin
B12.
Demonstration that yqhD is required for significant L3-propanediol production in
25 E. coli strain KLP23/DAH48/PKP32:
Fermentations for the production of 1,3-propanediol were performed, essentially as described in Example 7, with the E. coli strain KLP23 (yqhD-)/pAH48/pKP32 in order to test for the effect of the yqhD disruption on
1,3-propanediol production.
30 A representative 10-L fermentation using the knockout of the non-specific
catalytic activity, E. coli strain KLP23 (yqhD-)/pAH48/pKP32, is shown in Table
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9. The organism steadily accumulated cell mass and glycerol until the addition of vitamin B12 when the OD550 exceeded 30 A (10.4 h). Vitamin B12 was added as
a bolus addition of 8 mg at 10.4 h and thereafter vitamin B12 was continuously fed
at a rate of 1.32 mg/h. In the 4 h that followed B12 addition, glucose consumption
5 slowed, the oxygen utilization rate dropped and there was no further increase in optical density. Fermentation of glucose ceased and the glucose concentration in the tank accumulated. The highest titer of 1,3-propanediol obtained was 0.41 g/L. The organism was checked for its viability by plating a dilution series of the cells on agar plates containing ampicillin and spectinomycin. The plates were
10 incubated for 24 h in a 30 °C incubator. There were no viable colonies on the plate from the fermentation of E. coli KLP23 0?/iZ)-J/pAH48/pKP32, Table 11. By contrast, the cell suspension from a control tank to which no vitamin B12 was added continued to accrue cell mass and glycerol until the 10-L tank was full due to the complete addition of the glucose feed solution (Table 10). An agar
15 plate viability determination by dilution series of the cell suspension at the end of
this fermentation showed a viable cell count that was consistent with the total cell number estimated by the optical density value (Table 11).
TABLE 9
Representative fermentation summary of the failed conversion of glucose to 1,3-
20 propanediol (1,3-PD) using E. coli strain KLP23 (y^AZ)-;/pAH48/pKP32.
time (h) OD550 (AU) DO (%) glucose (g/L) glycerol (g/L) 1,3-PD (g/L)
0 0.4 150 11.3 0.05 0
2.3 3.0 134 10.7 0.13 0
4.3 10.8 85.0 8.2 1.41 0
8.3 23.1 81.8 0.9 10.0 0
16.3 37.2 149 13.1 21.4 0.41
18.3 47.6 149 18.9 21.6 0.39
20.3 39.6 149 24.4 22.3 0.42
23.8 33.6 149 25.4 22.0 0.41
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TABLE 10
Representative fermentation summary of the conversion of glucose to glycerol

using E. coli strin y
Time (h) OD55o(AU) DO (%) glucose (g/L) glycerol (g/L)
0 0.2 148 9.5 0.06
2.2 2.8 128 8.9 0.13
4.2 10.4 58.5 7.0 1-4
8.2 21.6 57,6 2.7 11.2
16.2 76.8 10.7 0 40.5
20.2 117 10.2 0 52.9
23.7 154 8.5 0 63.9
36.2 239 10.1 0.1 122
TABLE 11
Representative summary of viability plate counts from endpoints of fermentations of glucose using E. coli strain KLP23(yqhD-,)/pAH48/pKP32 in the absence and
presence of vitamin B12-

vitamin B12 time (h) at endpoint OD550 (AU) viable counts (cfu/mL)
no 36.2 239 2.1E11
yes 23.8 33.6 0
yes 23.8 41.2 0
69

We claim
1. A microorganism transformed with a chimeric gene comprising an isolated nucleic acid fragment encoding a non-specific catalytic
activity for the conversion of 3-hydroxypropionaldehyde to 1, 3-propanediol operably linked to suitable regulatory sequences, wherein the isolated nucleic acid fragment is selected from the group consisting of:
(a) an isolated nucleic acid fragment encoding the amino acid sequence of SEQ ID NO:57;
(b) an isolated nucleic acid fragment encoding a polypeptide of at least 387 amino acids having at least 80% identity with the amino acid sequence of SEQ ID NO:57;
(c) an isolated nucleic acid fragment that hybridizes with (a) or (b) under hybridization conditions of 0.1X SSC, 0.1% SDS, 65 °C and washed with 2X SSC, 0.1% SDS followed by 0.1X SSC, 0.1% SDS; and
(d) an isolated nucleic acid fragment that is complementary to (a) (b), or (c):
wherein the microorganism is selected from the group consisting of Citrobacter, Enterobacter, Clostridium, Klebsiella, Aerobacter, Lactobacillus, Aspergillus, Saccharomnyces, Schizosaccharomyces, Zygosaccharomyces, Pichia, Kluyveromyces, Candida, Debaryomyces, Mucor, Methylobacter, Salmonella, Bacillus, Streptomyces and Pseudomonas.
2. A recombinant- microorganism, useful for the production of 1,3-propanediol, comprising:
(a) at least one gene encoding a polypeptide having a dehydratase
activity;
75

(b).at least one gene encoding a dehydratase reactivation factor;
and
(c) at least one exogenous gene encoding an non-specific catalytic activity to convert 3 -hydroxypropionaldehyde to 1 ,3-propanediol; wherein no functional dhaT gene encoding a 1,3-propanediol oxidoreductase activity is present in the recombinant microorganism and the microorganism is selected from, the group consisting of Citrobacter, Enterobacter, Clostridium. kliebsiella, Aerobacter, Lacto bacillus, Aspergillus, Saccharomyces, Schizosaccharomyces, Zygosaccharomyces, Pichia, Kluyveromyces, Candida, Debaryomyces, Mucor, Methylobacter, Salmonella, Bacillus, Streptomyces and Pseudomonas.
3. The recombinant microorganism as claimed in Claim 2 wherein it
comprises:
. (a) at least one gene encoding a polypeptide having glycerol-3-phosphate dehydrogenase activity; and
(b) at least one gene encoding a polypeptide having glycerol-3-phsophatase activity.
4
4. The recombinant microorganism as claimed in Claim 2 or 3 wherein the dehydratase reactivation factor is encoded by orfX and orfZ, isolated from a dha regulon.
5. The recombinant microorganism as claimed in Claim 4 wherein orjX and orfZ are independently isolated from Klebsiella sp., Citrobacter sp.. or Clostridium sp.
6. The recombinant microorganism as claimed in Claim 3, wherein it
comprises a set of endogenous genes, each having a mutation inactivating the gene, the set consisting of:
(a) a first gene encoding a polypeptide having glycerol kinase
76

activity;
(b) a second gene encoding a polypeptide having glycerol
dehydrogenase activity;
and (e) a third gene encoding a polypeptide having triosephosphate isomerase activity.
7. ' The recombinant microorganism as claimed in Claims 3 or 6 wherein
the recombinant microorganism converts a carbon source selected from the
group consisting of monosaccharides, oligosaccharides, polysaccharides,
and single-carbon substrates to 1,3-propanediol.
*
8. The recombinant microorganism as claimed in Claim 2 wherein the
recombinant microorganism converts a carbon source selected from the
group consisting of glycerol and dihydroxyacet;one to 1,3-propanediol.
9. The recombinant microorganism 4 as claimed in Claims 3 or 6
wherein the gene encoding a polypeptide having glyercol-3-phosphate
dehydrogenase activity is selected from the group consisting of GPD1,
GPD2, GPD3, DAR1, gpsA, GUT2, glpD, and glpA BC. .
10 The recombinant microorganism as claimed in Claims 3 or 6 wherein the gene encoding a polypeptide having glycerol-3-phosphatase activity is selected from the group consisting of GPP 1 and GPP2.
11. The recombinant microorganism claimed in Claims 2, 3 or 6 wherein the gene encoding a polypeptide having a dehydratase activity is selected from the group consisting of a glycerol dehydratase and a diol dehydratase.
12 The recombinant microorganism as claimed in Claims 2, 3 and 6 wherein the gene encoding a polypeptide having a dehydratase activity is isolated from Klebsiella sp, Citrobacter sp.,. or Clostridiun sp.
77

13 A recombinant E. coli pomprising:
(a) a set of exogenous genes consisting of:
(i) at least one gene encoding a polypeptide having a glycerol or diol dehydratase activity;
(ii) at least one gene encoding a polypeptide having glycerol-3-phosphate dehydrogenase activity;
(iii) at least one gene encoding a polypeptide having glycerols-phosphatase activity; and
(iv) at least one gene encoding a dehydratase reactivation
factor; and
(b) at least one endogenous gene encoding a non-specific catalytic
activity to convert 3-hydroxypropionaldehyde to 1 ,3-propanediol:
wherein no functional dkaT gene encoding a 1 ,3-propanediol oxidoreductase activity is present in the recombinant E. coli.
14. A recombinant E. coli comprising:
(a) a set of exogenous genes consisting of
(i) at least one copy of dhaR. nucleotides 2209-4134 of SEQ
ID NO:l; (ii) at least one copy of orfK complementary to nucleotides
6202-6630 of SEQ ID NO:l; (iii) at least one copy of orfK complementary to nucleotides 4643-4996 of
SEQ ID NO: 1; (iv) at least one copy of orfW. complementary to nucleotides
4112-4642 of SEQ ID NO:l; (v) at least one copy of dhaBl, dhaB2, and dhaB3,
nucleotides 7044-8711 of SEQ ID NO:l, nucleotides
8724-9308 of SEQ ID NO:l, and nucleotides 931 1-9736
of SEQ ID NO:l, respectively, and (vi) at least on copy of orfZ, nucleotides 9749-11572 of SE
78

IDN0:1 and (b) at least one endogenous gene encoding a non-specific catalytic activity to convert 3-hydroxypropionaldehyde to 1 ,3 -propanediol, wherein no functional dhaT gene encoding a 1 ,3-propanediol oxidoreductase activity is present in the recombinant E. coli.
15. The recombinant E. coli as claimed in claim 14 wherein it comprises a
set of endogenous genes, each gene having a mutation inactivating the gene,
the set of endogenous genes consisting of:
(a) a gene encoding a polypeptide having glycerol kinase activity:;
(b) a gene encoding a polypeptide having glycerol dehydrogenase activity; and
(c) a gene encoding a polypeptide having triosephosphate isomerase activity.
16. A process for the bioproduction of 1,3-propanediol comprising:
(a) contacting under suitable conditions the recombinant E. coli as claimed in Claims 13, 14, or 15 with at least one carbon source selected from the group consisting of monosaccharides, oligosaccharides, polysaccharides, and single-carbon substrates whereby 1,3-propanediol is produced; and
(b) optionally recovering the 1,3-propanediol produced in (a).
17. A process for the bioproduction of 1,3-propanediol comprising:
(a) contacting under suitable conditions 1) a recombinant F. coli comprising (a) a set of exogenous genes consisting of
(i) at least one exogenous gene encoding a polypeptide having a glycerol or diol
dehydratase activity; and
(ii) at least one exogenous gene encoding a dehydratase reactivation factor; and
79

(b) at least one endogenous gene encoding a nonspecific catalytic activity to convert 3-
hydroxypropionaldehyde to I ,3-propanediol,
wherein no functional c/haT gene encoding a 1 ,3-propanediol
oxidoreductase activity is present in the recombinant E.coli or (2) the recombinant E. coli of Claim 14 with at least one carbon source selected from the group consisting of glycerol and dihydroxyactetone, and (b) optionally recovering the 1 ,3-propanediol produced in (a).
A process for the production of 1 ,3-propanediol comprising:
(a) contacting a recombinant E. coli with a first source of carbon
and with a second source of carbon, the recombinant E. coli
comprising:
(i) at least one exogenous gene encoding a polypeptide
having a glycerol or diol dehydratase activity; (ii) at least one exogenous gene encoding a dehydratase
reactivation factor;
(iii) at least one endogenous gene encoding a non-specific
catalytic activity
sufficient to convert 3-hydroxypropionaldehyde to I ,3 -propanediol, wherein no functional dhaT gene encoding a 1 ,3-propanediol oxidoreductase activity is present in the recombinant E .coli and wherein the first carbon source is selected from the group consisting of glycerol and dehydroxyacetone, and the second carbon source is selected from the group consisting of monosaccharides, ol igosaceharides, polysaccharides, and single-carbon substrates;
and
(b) optionally recovering the 1 ,3-propanediol produced in (a).
80

19. .The process as claimed in Claim 18 wherein the recombinant F. co/i
comprises
a set of exogenous genes consisting of
(a) at least one gene encoding a polypeptide having glycerol-3-
phosphate dehydrogenase activity; and
(b) at least one gene encoding a polypeptide having glycerol-3-
phosphatase activity and
20. The process of as claimed in Claim 19 wherein the recombinant E.coli further comprises
(i) a gene encoding a polypeptide having glycerol kinase activity
(ii) a gene encoding a polypeptide having glycerol
dehydrogenase activity; and (ii) a gene encoding a polypeptide having triosephosphate
isomerase activity.
21. A microorganism transformed with a chimeric gene substantially as herein described with reference to the foregoing examples.
22. A recombinant microorganism useful for the production of 1, 3-propanediol substantially as herein described with reference to the
foregoing examples. 23 A process for the bioproduction of 1, 3-propanediol substantially as herein described with reference to the foregoing examples.




N/A

Documents:

1280-MUMNP-2005-ABSTRACT(29-10-2008).pdf

1280-MUMNP-2005-ABSTRACT(AMENDED)-(29-10-2008).pdf

1280-MUMNP-2005-ABSTRACT(GRANTED)-(30-3-2009).pdf

1280-MUMNP-2005-CANCELLED PAGES(29-10-2008)-1.pdf

1280-MUMNP-2005-CANCELLED PAGES(29-10-2008).pdf

1280-MUMNP-2005-CLAIMS(21-11-2005).pdf

1280-MUMNP-2005-CLAIMS(29-10-2008).pdf

1280-MUMNP-2005-CLAIMS(GRANTED)-(30-3-2009).pdf

1280-mumnp-2005-claims.doc

1280-mumnp-2005-claims.pdf

1280-MUMNP-2005-CORRESPONDENCE(17-5-2006).pdf

1280-MUMNP-2005-CORRESPONDENCE(2-4-2012).pdf

1280-MUMNP-2005-CORRESPONDENCE(2-6-2009).pdf

1280-MUMNP-2005-CORRESPONDENCE(29-10-2008).pdf

1280-MUMNP-2005-CORRESPONDENCE(IPO)-(6-4-2009).pdf

1280-mumnp-2005-correspondence-others.pdf

1280-mumnp-2005-correspondence-received-ver-181105.pdf

1280-mumnp-2005-correspondence-received.pdf

1280-mumnp-2005-description (complete).pdf

1280-MUMNP-2005-DESCRIPTION(COMPLETE)-(21-11-2005).pdf

1280-MUMNP-2005-DESCRIPTION(COMPLETE)-(29-10-2008).pdf

1280-MUMNP-2005-DESCRIPTION(GRANTED)-(30-3-2009).pdf

1280-MUMNP-2005-DRAWING(21-11-2005).pdf

1280-MUMNP-2005-DRAWING(29-10-2008).pdf

1280-MUMNP-2005-DRAWING(GRANTED)-(30-3-2009).pdf

1280-mumnp-2005-drawings.pdf

1280-MUMNP-2005-FORM 1(21-11-2005).pdf

1280-MUMNP-2005-FORM 1(29-10-2008).pdf

1280-mumnp-2005-form 13(2-6-2009).pdf

1280-mumnp-2005-form 13(29-10-2008).pdf

1280-MUMNP-2005-FORM 18(17-5-2006).pdf

1280-mumnp-2005-form 2(29-10-2008).pdf

1280-MUMNP-2005-FORM 2(COMPLETE)-(21-11-2005).pdf

1280-MUMNP-2005-FORM 2(GRANTED)-(30-3-2009).pdf

1280-MUMNP-2005-FORM 2(TITLE PAGE)-(21-11-2005).pdf

1280-MUMNP-2005-FORM 2(TITLE PAGE)-(29-10-2008).pdf

1280-MUMNP-2005-FORM 2(TITLE PAGE)-(GRANTED)-(30-3-2009).pdf

1280-MUMNP-2005-FORM 3(21-11-2005).pdf

1280-MUMNP-2005-FORM 3(29-10-2008).pdf

1280-MUMNP-2005-FORM 5(21-11-2005).pdf

1280-MUMNP-2005-FORM 5(29-10-2008).pdf

1280-mumnp-2005-form-1.pdf

1280-mumnp-2005-form-2.doc

1280-mumnp-2005-form-2.pdf

1280-mumnp-2005-form-3.pdf

1280-mumnp-2005-form-5.pdf

1280-MUMNP-2005-OTHER DOCUMENT(29-10-2008).pdf

1280-MUMNP-2005-PETITION UNDER RULE-138(2-4-2012).pdf

1280-MUMNP-2005-POWER OF AUTHORITY(29-10-2008).pdf

1280-MUMNP-2005-SEQUENCE LISTING(29-10-2008).pdf

1280-MUMNP-2005-SPECIFICATION(AMENDED)-(29-10-2008).pdf

1280-MUMNP-2005-WO INTERNATIONAL PUBLICATION REPORT(21-11-2005).pdf

BC1020 PCT SEQ.TXT


Patent Number 233399
Indian Patent Application Number 1280/MUMNP/2005
PG Journal Number 14/2009
Publication Date 03-Apr-2009
Grant Date 30-Mar-2009
Date of Filing 21-Nov-2005
Name of Patentee E.I.DU PONT DE NEMOURS AND COMPANY
Applicant Address 1007 MARKET STREET, WILMINGTON, DELAWARE 19898
Inventors:
# Inventor's Name Inventor's Address
1 MARK EMPTAGE 2822 LONDON DRIVE, WILMINGTON, DE 19810
2 SHARON HAYNIE 529 SPRUCE STREET, PHILADELPHIA, PA 19106
3 JEFF PUCCI 925 PAGE MILL ROAD, PALO ALTO, CALIFORNIA 94303
4 LISA LAFFEND 2 MOUNT VERNON DRIVE, CLAYMONT, DE 19703
5 GREG WHITED 304 SOUTH ROAD, BELMONT, CALIFORNIA 94002
PCT International Classification Number C12P7/00
PCT International Application Number PCT/US00/22874
PCT International Filing date 2000-08-18
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 60/149,534 1999-08-18 U.S.A.