Several novel PHA polymer compositions produced using biological systems include monomers such as 3-hydroxybutyrate, 3-hydroxypropionate, 2-hydroxybutyrate, 3-hydroxyvalerate, 4-hydroxybutyrate, 4-hydroxyvalerate and 5-hydroxyvalerate. These PHA compositions can readily be extended to incorporate additional monomers including, for example, 3-hydroxyhexanoate, 4-hydroxyhexanoate, 6-hydroxyhexanoate or other longer chain 3-hydroxyacids containing seven or more carbons. This can be accomplished by taking natural PHA producers and mutating through chemical or transposon mutagenesis to delete or inactivate genes encoding undesirable activities. Alternatively, the strains can be genetically engineered to express only those enzymes required for the production of the desired polymer composition. Methods for genetically engineering PHA producing microbes are widely known in the art (Huisman and Madison, 1998, Microbiology and Molecular Biology Reviews, 63: 21-53). These polymers have a variety of uses in medical, industrial and other commercial areas.

BACKGROUND TO THE INVENTION
 Numerous microorganisms have the ability to accumulate intracellular
 reserves of PHA polymers. Poly [(R)-3-hydroxyalkanoates] (PHAs) are
 biodegradable and biocompatible thermoplastic materials, produced from
 renewable resources, with a broad range of industrial and biomedical
 applications (Williams and Peoples, 1996, CHEMTECH 26, 38-44). Around 100
 different monomers have been incorporated into PHA polymers, as reported
 in the literature (Steinbuchel and Valentin, 1995, FEMS Microbiol. Lett.
 128; 219-228) and the biology and genetics of their metabolism has
 recently been reviewed (Huisman and Madison, 1998, Microbiology and
 Molecular Biology Reviews, 63: 21-53).
 To date, PHAs have seen limited commercial availability, with only the
 copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) being
 available in development quantities. This copolymer has been produced by
 fermentation of the bacterium Ralstonia eutropha. Fermentation and
 recovery processes for other PHA types have also been developed using a
 range of bacteria including Azotobacter, Alcaligenes latus, Comamonas
 testosterone and genetically engineered E. coli and Klebsiella and have
 recently been reviewed (Braunegg et al., 1998, Journal of Biotechnology
 65: 127-161; Choi and Lee, 1999, Appl. Microbiol. Biotechnol. 51: 13-21).
 More traditional polymer synthesis approaches have also been examined,
 including direct condensation and ring-opening polymerization of the
 corresponding lactones (Jesudason and Marchessault, 1994, Macromolecules
 27: 2595-2602).
 Synthesis of PHA polymers containing the monomer 4-hydroxybutyrate (PHB4HB,
 Doi, Y. 1995, Macromol. Symp. 98, 585-599) or 4-hydroxyvalerate and
 4-hydroxyhexanoate containing PHA polyesters have been described (Valentin
 et al., 1992, Appl. Microbiol. Biotechnol. 36, 507-514 and Valentin et
 al., 1994, Appl. Microbiol. Biotechnol. 40, 710-716). These polyesters
 have been manufactured using methods similar to that originally described
 for PHBV in which the microorganisms are fed a relatively expensive
 non-carbohydrate feedstock in order to force the incorporation of the
 monomer into the PHA polyester. The PHB4HB copolymers can be produced with
 a range of monomer compositions which again provides a range of polymer
 (Saito, Y, Nakamura, S., Hiramitsu, M. and Doi, Y., 1996, Polym. Int. 39:
 169).
 PHA copolymers of 3-hydroxybutyrate-co-3-hydroxypropionate have also been
 described (Shimamura et. al., 1994, Macromolecules 27: 4429-4435; Cao et.
 al., 1997, Macromol. Chem. Phys. 198: 3539-3557). The highest level of
 3-hydroxypropionate incorporated into these copolymers 88 mol % (Shimamura
 et. al., 1994, Macromolecules 27: 4429-4435).
 PHA terpolymers containing 4-hydroxyvalerate have been produced by feeding
 a genetically engineered Pseudomonas putida strain on 4-hydroxyvalerate or
 levulinic acid which resulted in a three component PHA,
 Poly(3-hydroxybutyrate-co-3-hydroxyvalerate-4-hydroxyvalerate) (Valentin
 et. al., 1992, Appl. Microbiol. Biotechnol. 36: 507-514; Steinbuchel and
 Gorenflo, 1997, Macromol. Symp. 123: 61-66). It is desirable to develop
 biological systems to produce two component polymers comprising
 4-hydroxyvalerate or poly(4-hydroxyvalerate) homopolymer. The results of
 Steinbuchel and Gorenflo (1997, Macromol. Symp. 123: 61-66) indicate that
 Pseudomonas putida has the ability to convert levulinic acid to
 4-hydroxyvalerate.
 Hein et al. (1997) attempted to synthesize poly-4HV using transgenic
 Escherichia coli strain XL1-Blue but were unsuccessful. These cells
 carried a plasmid which permitted expression of the A. eutrophus PHA
 synthase and the Clostridium kluyveri 4-hydroxybutyryl-CoA transferase
 genes. When the transgenic E. coli were fed 4HV,
 .quadrature.-valerolactone, or levulinic acid, they produced only a small
 amount of PHB homopolymer.
 It is clearly desirable for industrial reasons to be able to produce a
 range of defined PHA homopolymer, copolyer and terpolymer compositions. To
 accomplish this, it is desirable to be able to control the availability of
 the individual enzymes in the corresponding PHA biosynthetic pathways.
 It is therefore an object of the present invention to provide a range of
 defined PHA homopolymer, copolyer and terpolymer compositions.
 It is another object of the present invention to provide a method and
 materials to control the availability of the individual enzymes in the
 corresponding PHA biosynthetic pathways.
 SUMMARY OF THE INVENTION
 Several novel PHA polymer compositions produced using biological systems
 include monomers such as 3-hydroxybutyrate, 3-hydroxypropionate,
 2-hydroxybutyrate, 3-hydroxyvalerate, 4-hydroxybutyrate, 4-hydroxyvalerate
 and 5-hydroxyvalerate. These PHA compositions can readily be extended to
 incorporate additional monomers including, for example,
 3-hydroxyhexanoate, 4-hydroxyhexanoate, 6-hydroxyhexanoate or other longer
 chain 3-hydroxyacids containing seven or more carbons. This can be
 accomplished by taking natural PHA producers and mutating through chemical
 or transposon mutagenesis to delete or inactivate genes encoding
 undesirable activities. Alternatively, the strains can be genetically
 engineered to express only those enzymes required for the production of
 the desired polymer composition. Methods for genetically engineering PHA
 producing microbes are widely known in the art (Huisman and Madison, 1998,
 Microbiology and Molecular Biology Reviews, 63: 21-53). These polymers
 have a variety of uses in medical, industrial and other commercial areas.

DETAILED DESCRIPTION OF THE INVENTION
 Several novel PHA polymer compositions have been produced using biological
 systems to incorporate monomers such as 3-hydroxybutyrate,
 3-hydroxypropionate, 2-hydroxybutyrate, 3-hydroxyvalerate,
 4-hydroxybutyrate, 4-hydroxyvalerate and 5-hydroxyvalerate. These PHA
 compositions can readily be extended to incorporate additional monomers
 including, for example, 3-hydroxyhexanoate, 4-hydroxyhexanoate,
 6-hydroxyhexanoate or other longer chain 3-hydroxyacids containing seven
 or more carbons. Techniques and procedures to engineer transgenic
 organisms that synthesize PHAs containing one or more of these monomers
 either as sole constituent or as co-monomer have been developed. In these
 systems the transgenic organism is either a bacterium eg. Escherichia
 Coli, K. pneumoniae, Ralstonia eutropha (formerly Alcaligenes eutrophus),
 Alcaligenes latus or other microorganisms able to synthesize PHAs, or a
 higher plant or plant component, such as the seed of an oil crop
 (Brassica, sunflower, soybean, corn, safflower, flax, palm or coconut or
 starch accumulating plants (potato, tapioca, cassava).
 It is crucial for efficient PHA synthesis in recombinant E. coli strains
 that the expression of all the genes involved in the pathway be adequate.
 To this end, the genes of interest can be expressed from extrachromosomal
 DNA molecules such as plasmids, which intrinsically results in a copy
 number effect and consequently high expression levels, or, more
 preferably, they can be expressed from the chromosome. For large scale
 fermentations of commodity type products it is generally known that
 plasmid-based systems are unsatisfactory due to the extra burden of
 maintaining the plasmids and the problems of stable expression. These
 drawbacks can be overcome using, chromosomally encoded enzymes by
 improving the transcriptional and translational signals preceding the gene
 of interest such that expression is sufficient and stable.
 The biological systems must express one or more enzymes as required to
 convert the monomers into polymers. Suitable substrates include
 3-hydroxybutyrate, 3-hydroxypropionate, 2-hydroxybutyrate,
 3-hydroxyvalerate, 4-hydroxybutyrate, 4-hydroxyvalerate,
 5-hydroxyvalerate, 3-hydroxyhexanoate, 4-hydroxyhexanoate,
 6-hydroxyhexanoate and other longer chain 3-hydroxyacids containing seven
 or more carbons. These enzymes include polyhydroxyalkanoate synthase,
 acyl-CoA transferase and hydroxyacyl CoA transferase, and hydroxyacyl CoA
 synthetase. These enzymes can be used with these substrates to produce in
 a biological system such as bacteria, yeast, fungi, or plants, polymer
 such as poly(3-hydroxybutyrate-co-4-hydroxyvalerate),
 poly(4-hydroxyvalerate), poly(3-hydroxypropionate-co-5-hydroxyvalerate),
 poly(2-hydroxybutyrate), poly(2-hydroxybutyrate-co-3-hydroxybutyrate), and
 poly(3-hydroxypropionate).
 Genes encoding the required enzymes can be acquired from multiple sources.
 U.S. Pat. Nos. 5,798,235 and 5,534,432 to Peoples, et al., describe
 polyhydroxyalkanoate synthetase, reductase and thiolase. A
 4-hydroxybutyryl CoA transferase gene from C. aminobutyricum is described
 by Willadsen and Buckel, FEMS Microbiol. Lett. (1990) 70: 187-192) or from
 C. kluyveri is described by Sohling and Gottschalk, 1996, J. Bacteriol.
 178, 871-880). An acyl coenzyme A synthetase from Neurospora crassa is
 described by Hii and Courtright, J. Bacteriol. 1982. 150(2), 981-983. A
 hydroxyacyl transferase from Clostridium is described by Hofmeister and
 Bucker, Eur. J. Biochem. 1992, 206(2), 547-552.
 It is important for efficient PHA production that strains do not lose the
 capability to synthesize the biopolymer for the duration of the inoculum
 train and the production run. Loss of any of the pha genes results in loss
 of product. Both are undesirable and stable propagation of the strain is
 therefore required. Merely integrating the gene encoding the transferase
 or synthase may not result in significant polymer production. Enzyme
 expression can be enhanced through alteration of the promoter region or
 mutagenesis or other known techniques, followed by screening for polymer
 production. Growth and morphology of these recombinant PHA producers is
 not compromised by the presence of pha genes on the chromosome.
 The present invention will be further understood by reference to the
 following non-limiting examples.
 EXAMPLE 1
 Poly(3HB-co-4HV) from 4-hydroxyvalerate and Glucose in E. coli.
 Construction of pFS16
 The plasmid pTrcN is a derivative of pTrc99a (Pharmacia; Uppsala, Sweden);
 the modification that distinguishes pTrcN is the removal of the Ncol
 restriction site by digestion with NcoI, treatment with T4 DNA polymerase,
 and self-ligation. The orfZ gene encoding the 4-hydroxybutyryl-CoA
 transferase from Clostridium kluyveri was amplified using the polymerase
 chain reaction (PCR) and a kit from Perkin Elmer (Foster City, Calif.)
 using plasmid pCK3 (Sohling and Gottschalk, 1996, J. Bacteriol. 178:
 871-880) as the target DNA and the following oligonucleotide primers:
 5'-TCCCCTAGGATTCAGGAGGTTTTTATGGAGTGGGAAGAGATATATAAAG -3'
 (orfZ 5' AvrII)
 5'-CCTTAAGTCGACAAATTCTAAAATCTCTTTTTAAATTC-3'
 (orfZ 3' SalI)
 The resulting PCR product was digested with AvrII and SalI and ligated to
 pTrcN that had been digested with XbaI (which is compatible with AvrII)
 and SalI to form plasmid pFS16 such that the 4-hydroxybutyryl-CoA
 transferase can be expressed from the IPTG
 (isopropyl-.beta.-D-glucopyranoside)--inducible trcpromoter.
 Construction of pFS30.
 The plasmid pFS30 was derived from pFS16 by adding the Ralstonia eutropha
 PHA synthase (phaC) gene (Peoples and Sinskey, 1989. J. Biol. Chem.
 264:15298-15303) which had been modified by the addition of a strong E.
 coli ribosome binding site as described by (Gerngross et. al., 1994.
 Biochemistry 33: 9311-9320). The plasmid pAeT414 was digested with XmaI
 and StuI so that the R. eutropha promoter and the structural phaC gene
 were present on one fragment. pFS16 was cut with BamHI, treated with T4
 DNA polymerase to create blunt ends, then digested with XmaI. The two DNA
 fragments thus obtained were ligated together to form pFS30. In this
 construct the PHB synthase and 4-hydroxybutyryl-CoA transferase are
 expressed from the A. eutrophus phbC promoter (Peoples and Sinskey, 1989.
 J. Biol. Chem. 264:15298-15303). Other suitable plasmids expressing PHB
 synthase and 4-hydroxybutyryl-CoA transferase have been described (Hein
 et. al., 1997, FEMS Microbiol. Lett. 153: 411-418; Valentin and Dennis,
 1997, J. Biotechnol. 58 :33-38).
 E. coli MBX769 has a PHA synthase integrated into its chromosome. This
 strain is capable of synthesizing, poly(3-hydroxybutyrate) (PUB) from
 glucose with no extrachromosomal genes present. MBX769is also deficient in
 fadR, the repressor of the fatty-acid-degradation pathway and effector of
 many other cellular functions, it is deficient in rpoS, a regulator of
 stationary-phase gene expression, and it is deficient in atoA, one subunit
 of the acetoacetyl-CoA transferase. MBX769 also expresses atoC, a positive
 regulator of the acetoacetate system, constitutively.
 E. coli MBX769 carrying the plasmid pFS16 (FIG. 2), which permitted the
 expression of the Clostridium kluyveri 4-hydroxybutyryl-CoA transferase,
 was precultured at 37.degree. C. in 100 mL of LB medium containing 100
 .mu.g/mL sodium ampicillin in a 250-mL Erlenmeyer flask with shaking at
 200 rpm. The cells were centrifuged at 5000 g for 10 minutes to remove
 them from the LB medium after 16 hours, and they were resuspended in 100
 mL of a medium containing, per liter: 4.1 or 12.4 g sodium
 4-hydroxyvalerate (4HV); 5 g/L sodium 4-hydroxybutyrate (4HB); 2 g
 glucose; 2.5 g LB broth powder (Difco; Detroit, Mich.); 50 mmol potassium
 phosphate, pH 7; 100 .mu.g/mL sodium ampicillin; and 0.1 mmol
 isopropyl-.beta.-D-thiogalactopyranoside (IPTG). The sodium
 4-hydroxyvalerate was obtained by saponification of .gamma.-valerolactone
 in a solution of sodium hydroxide. The cells were incubated in this medium
 for 3 days with shaking at 200 rpm at 32.degree. C. in the same flask in
 which they had been precultured. When 4.1 g/L sodium 4-hydroxyvalerate was
 present initially, the cells accumulated a polymer to 52.6% of the dry
 cell weight that consisted of 63.4% 3HB units and 36.6% 4HB units but no
 4HV units.
 When 12.4 g/L sodium 4HV was present initially, the cells accumulated a
 polymer to 45.9% of the dry cell weight that consisted of 95.5% 3HB units
 and 4.5% 4HV units but no detectable 4HB units. The identity of the
 PHB-co-4HV polymer was verified by nuclear magnetic resonance (NMR)
 analysis of the solid product obtained by chloroform extraction of whole
 cells followed by filtration, ethanol precipitation of the polymer from
 the filtrate, and washing of the polymer with water. It was also verified
 by gas chromatographic (GC) analysis, which was carried out as follows.
 Extracted polymer (1-20 mg) or lyophilized whole cells (15-50 mg) were
 incubated in 3 mL of a propanolysis solution consisting of 50%
 1,2-dichloroethane, 40% 1-propanol, and 10% concentrated hydrochloric acid
 at 100.degree. C. for 5 hours. The water-soluble components of the
 resulting mixture were removed by extraction with 3 mL water. The organic
 phase (1 .mu.L at a split ratio of 1:50 at an overall flow rate of 2
 mL/min) was analyzed on an SPB-1 fused silica capillary GC column (30 m;
 0.32 mm ID; 0.25 .mu.m film; Supelco; Bellefonte, Pa.) with the following
 temperature profile: 80.degree. C., 2 min; 10.degree. C. per min to
 250.degree. C.; 250.degree. C., 2 min. The standard used to test for the
 presence of 4HV units in the polymer was .gamma.-valerolactone, which,
 like 4-hydroxyvaleric acid, forms propyl 4-hydroxyvalerate upon
 propanolysis. The standard used to test for 3HB units in the polymer was
 PHB.
 EXAMPLE 2
 Poly(4HV) from 4-hydroxyvalerate in E. coli
 Escherichia coli MBX1177 is not capable of synthesizing
 poly(3-hydroxybutyrate) (PHB) from glucose. MBX1177 is a spontaneous
 mutant of strain DH5.quadrature. that is able to use 4-hydroxybutyric acid
 as a carbon source. MBX1177 carrying the plasmid pFS30 (FIG. 2), which
 permitted the expression of the Clostridium kluyveri 4HB-CoA transferase
 and the Ralstonia eutropha PHA synthase, was precultured at 37.degree. C.
 in 100 mL of LB medium containing 100 .mu.g/mL sodium ampicillin.
 The cells were centrifuged at 5000 g for 10 minutes to remove them from the
 LB medium after 16 hours, and they were resuspended in 100 mL of a medium
 containing, per liter: 5 g sodium 4-hydroxyvalerate (4HV); 2 g glucose;
 2.5 g LB broth powder; 100 mmol potassium phosphate, pH 7; 100 .mu.g/mL
 sodium ampicillin; and 0.1 mmol IPTG. The cells were incubated in this
 medium for 3 days with shaking at 200 rpm at 30.degree. C. in the same
 flask in which they had been precultured.
 The cells accumulated a polymer to 0.25% of the dry cell weight that
 consisted of 100% 4HV units. The identity of the poly(4HV) polymer was
 verified by GC analysis of whole cells that had been washed with water and
 propanolyzed in a mixture of 50% 1,2-dichloroethane, 40% 1-propanol, and
 10% concentrated hydrochloric acid at 100.degree. C. for 5 hours, with
 .gamma.-valerolactone as the standard.
 EXAMPLE 3
 Poly(3HB-co-2HB) from 2-hydroxybutyrate and Glucose in E. coli
 E. coli MBX769 carrying the plasmid pFS16 was precultured at 37.degree. C.
 in 100 mL of LB medium containing 100 .mu.g/mL sodium ampicillin in a
 250-mL Erlenmeyer flask with shaking at 200 rpm. The cells were
 centrifuged at 5000 g for 10 minutes to remove them from the LB medium
 after 16 hours, and they were resuspended in 100 mL of a medium
 containing, per liter: 5 g sodium 2-hydroxybutyrate (2HB); 2 g glucose;
 2.5 g LB broth powder; 50 mmol potassium phosphate, pH 7; 100 .mu.g/mL
 sodium ampicillin; and 0.1 mmol IPTG. The cells were incubated in this
 medium for 3 days with shaking at 150 rpm at 33.degree. C. in the same
 flask in which they had been precultured. The cells accumulated a polymer
 to 19.0% of the dry cell weight that consisted of 99.7% 3HB units and 0.3%
 2HB units. The identity of the poly(3HB-co-2HB) polymer was verified by GC
 analysis of the solid product obtained by chloroform extraction of whole
 cells followed by filtration, ethanol precipitation of the polymer from
 the filtrate, and washing of the polymer with water. It was also verified
 by GC analysis of whole cells that had been washed with water and
 propanolyzed in a mixture of 50% 1,2-dichloroethane, 40% 1-propanol, and
 10% concentrated hydrochloric acid at 100.degree. C. for 5 hours, with PHB
 and sodium 2-hydroxybutyrate as the standards.
 EXAMPLE 4
 Poly(2HB) from 2-hydroxybutyrate in E. coli
 Escherichia coli MBX184 is not capable of synthesizing
 poly(3-hydroxybutyrate) (PHB) from glucose. MBX184 is deficient in fadR
 and expresses atoC constitutively.
 MBX184 carrying the plasmid pFS30 was precultured at 37.degree. C. in 100
 mL of LB medium containing 100 .mu.g/mL sodium ampicillin. The cells were
 centrifuged at 5000 g for 10 minutes to remove them from the LB medium
 after 16 hours, and they were resuspended in 100 mL of a medium
 containing, per liter: 5 g sodium 2-hydroxybutyrate (2HB); 2 g glucose;
 2.5 g LB broth powder; 50 mmol potassium phosphate, pH 7; 100 .mu.g/mL
 sodium ampicillin; and 0.1 mmol IPTG. The cells were incubated in this
 medium for 3 days with shaking at 150 rpm at 33.degree. C. in the same
 flask in which they had been precultured.
 The cells accumulated a polymer to 1.0% of the dry cell weight that
 consisted of 100% 2HB units. The identity of the poly(2HB) polymer was
 verified by GC analysis of whole cells that had been washed with water and
 propanolyzed in a mixture of 50% 1,2-dichloroethane, 40% 1-propanol, and
 10% concentrated hydrochloric acid at 100.degree. C. for 5 hours, with
 sodium 2-hydroxybutyrate as the standard.
 EXAMPLE 5
 Poly-3HP and poly-3HP-co-5HV from 1,3-propanediol and from 1,5-pentanediol.
 Escherichia coli MBX184 carrying the plasmid pFS30 was precultured at
 37.degree. C. in 100 mL of LB medium containing 100 .mu.g/mL sodium
 ampicillin. The cells were centrifuged at 5000 g for 10 minutes to remove
 them from the LB medium after 16 hours, and they were resuspended in 100
 mL of a medium containing, per liter: 10 g 1,3-propanediol (1,3-PD) or
 1,5-pentanediol (1,5-PD); 2 g glucose; 2.5 g LB broth powder; 50 mmol
 potassium phosphate, pH 7; 100 .mu.g/mL sodium ampicillin; and 0.1 mmol
 IPTG. The cells were incubated in this medium for 3 days with shaking at
 200 rpm at 30.degree. C. in the same flask in which they had been
 precultured. When the diol substrate was 1,3-PD, the cells accumulated a
 polymer to 7.0% of the dry cell weight that consisted entirely of 3HP
 units. When the substrate was 1,5-PD, the cells accumulated a polymer to
 22.1 % of the dry cell weight that consisted of greater than 90%
 3-hydroxypropionate units and less than 10% 5-hydroxyvalerate units. The
 identity of the poly(3-hydroxypropionate) polymer was verified by NMR
 analysis of the solid product obtained by sodium hypochlorite extraction
 of whole cells followed by centrifugation and washing of the polymer with
 water. The identity of both polymers was verified by GC analysis of sodium
 hypochlorite-extracted polymer that was propanolyzed in a mixture of 50%
 1,2-dichloroethane, 40% 1-propanol, and 10% concentrated hydrochloric acid
 at 100.degree. C. for 5 hours, with .beta.-propiolactone and
 .delta.-valerolactone as the standards.
 EXAMPLE 6
 Poly-5HV from 5-hydroxyvaleric acid
 Escherichia coli MBX1177 carrying the plasmid pFS30 was precultured at
 37.degree. C. in 50 mL of LB medium containing 100 .mu.g/mL sodium
 ampicillin. The cells were centrifuged at 5000 g for 10 minutes to remove
 them from the LB medium after 8 hours, and they were resuspended in 100 mL
 of a medium containing, per liter: 10 g sodium 5-hydroxyvalerate (5HV); 5
 g glucose; 2.5 g LB broth powder; 50 mmol potassium phosphate, pH 7; 100
 .mu.g/mL sodium ampicillin; and 0.1 mmol IPTG. The sodium 5HV was obtained
 by saponification of d-valerolactone. The cells were incubated in this
 medium for 3 days with shaking at 200 rpm at 30.degree. C. in the same
 flask in which they had been precultured. GC analysis was conducted with
 lyophilized whole cells that were butanolyzed in a mixture of 90%
 1-butanol and 10% concentrated hydrochloric acid at 110.degree. C. for 5
 hours; the standard was sodium 5-hydroxyvalerate. This analysis showed
 that the cells had accumulated poly(5HV) to 13.9% of the dry cell weight.
 The identity of the poly(5-hydroxyvalerate) polymer was verified by NMR
 analysis of the solid product obtained by 1,2-dichloroethane extraction of
 whole cells followed by centrifugation and washing of the polymer with
 water.
 Modifications and variations are intended to come within the scope of the
 appended claims.
 SEQUENCE LISTING
 &lt;100&gt; GENERAL INFORMATION:
 &lt;160&gt; NUMBER OF SEQ ID NOS: 2
 &lt;200&gt; SEQUENCE CHARACTERISTICS:
 &lt;210&gt; SEQ ID NO 1
 &lt;211&gt; LENGTH: 49
 &lt;212&gt; TYPE: DNA
 &lt;213&gt; ORGANISM: Artificial Sequence
 &lt;220&gt; FEATURE:
 &lt;223&gt; OTHER INFORMATION: Description of Artificial Sequence
 Primer- orfZ 5' AvrII
 &lt;400&gt; SEQUENCE: 1
 tcccctagga ttcaggaggt ttttatggag tgggaagaga tatataaag 49
 &lt;200&gt; SEQUENCE CHARACTERISTICS:
 &lt;210&gt; SEQ ID NO 2
 &lt;211&gt; LENGTH: 38
 &lt;212&gt; TYPE: DNA
 &lt;213&gt; ORGANISM: Artificial Sequence
 &lt;220&gt; FEATURE:
 &lt;223&gt; OTHER INFORMATION: Description of Artificial Sequence
 Primer- orfZ 3' SalI
 &lt;400&gt; SEQUENCE: 2
 ccttaagtcg acaaattcta aaatctcttt ttaaattc 38