Recycling of petrochemical plastics into pha

Abstract

The present disclosure provides a method for forming a PHA which includes mixing a mixing a petroleum-derived polymer or partially petroleum-derived polymer with a depolymerase enzyme and reacting the polymer with the depolymerase enzyme to produce a second mixture which includes a plurality of polymer degradation products. The depolymerase enzyme is denatured and the polymer degradation products are mixed with microorganisms which include polyhydroxyalkanoate-accumulating bacteria and fermented so that the microorganisms consume at least a portion of the polymer degradation products and intercellularly synthesize at least one polyhydroxyalkanoate.

Description

RECYCLING OF PETROCHEMICAL PLASTICS INTO PHACROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and benefit of U.S. Provisional Application No. 63 / 691,625, filed on September 6, 2024, the entire disclosure of which is incorporated by reference in its entirety.FIELD

[0002] This disclosure relates to biodegradable polymers. More particularly, this disclosure related to methods for degrading petroleum-derived polymer or partially petroleum-derived polymer and using the resultant degradation products to produce biodegradable polyhydroxy alkanoates .BACKGROUND

[0003] Polyhydroxyalkanoates (PHAs) are a class of biobased polymers of increasing commercial interest, which are also biodegradable and / or compostable. Polyhydroxyalkanoates are mostly commonly produced through bio-fermentation in which a carbon source (i.e., a food source) is converted by bacteria or other microbes into the desired poly hydroxy alkanoates. The carbon sources which are used in this biofermentation are typically derived from plant oils, hemicellulose, animal oils, sugars, and / or residue from distillation of vegetable oils.

[0004] While these carbon sources have been adequate thus far, it would be desirable to provide alternative carbon sources which could be used in the production of polyhydroxyalkanoates, as commercial interest in polyhydroxyalkanoates grows over time.

[0005] In particular, it would be desirable to produce polyhydroxyalkanoates using plastic waste products formed from petroleum-based polymers as a carbon feed source.SUMMARY

[0007] The above and other needs are met by a method for forming a polyhydroxyalkanoate according to the present disclosure. According to one embodiment, the method includes a step of extracellularly mixing a petroleum-derived polymer or partially petroleum-derived polymer having an initial weight average molecular weight with a depolymerase enzyme to form an initial aqueous mixture. The amount of the depolymerase enzyme in this initial aqueous mixture is from about 0.0005 percent to about 50 percent of the amount of the initial petroleum-derived polymer or partially petroleum- derived polymer, by weight.

[0008] The initial petroleum-derived polymer or partially petroleum-derived polymer is reacted with the depolymerase enzyme for at least two hours to produce a second mixture which includes a plurality of polymer degradation products. These polymer degradation products in the second mixture have a final weight average molecular weight which is at least 10 percent less than the initial weight average molecular weight of the initial petroleum-derived polymer or partially petroleum-derived polymer, wherein all weight average molecular weights are determined in accordance with ASTM D5296.

[0009] The method then includes a step of denaturing the depolymerase enzyme and a step of mixing the polymer degradation products with microorganisms which include polyhydroxyalkanoate-accumulating bacteria. The polymer degradation products and the microorganisms are then fermented at a temperature from about 25 °C to about 60 °C for a period of at least 24 hours so that the microorganisms consume at least a portion of the polymer degradation products and intercellularly synthesize at least one polyhydroxyalkanoate; and

[0010] Finally, the at least one polyhydroxyalkanoate is separated from the microorganisms .

[0011] According to certain embodiments, the initial aqueous mixture preferably also includes at least one additive selected from the group consisting of emulsifiers, glycerol, inorganic salts, carbon feedstocks, acids, bases, and mixtures thereof.

[0012] In some embodiments, the polyhydroxyalkanoate-accumulating bacteria is preferably made up of mcsophilic bacteria selected from the group consisting of Cupriavidus sp., Pseudomonas sp., Escherichia sp., Bacillus sp., Lysinibacillus sp., Brevibacillus sp, Phanerochaete chrysoporium, Comamonas sp., Delftia sp., Penicillium simplicissimum, Rhodococcus ruber, Ideonella sakaiensis, Staphylococcus sp., Chromobacterium sp., Alcaligenes eutrophus, Ralstonia eutropha, Rhodobacter sphaeroides, Pseudomonas sp., Escherichia coli, Wautersia eutropha, Hydrogenophaga pseudoflava, Saccharophagus degradans, Azohydromonas lata, Methylobacterium sp., Azotobacter sp., Burkholderia sp., Zobellella denitrificans, Aeromonas sp., Erwinia sp., Mari obacter sp., Azo spire sp., Aspergillus eutrophus and mixtures thereof.

[0013] In certain embodiments, the polyhydroxyalkanoate-accumulating bacteria is preferably made up of halophilic bacteria selected from the group consisting of Haloarcula sp., Haloferax sp., Halopiger sp., Haloquadratum sp., Halobacterium sp., Halostagnicola sp., Haloterrigena sp., Halobiforma sp., Halococcus sp., Halorubrum sp., Halalkalicoccus sp., Halogeometricum sp., Halogranum sp., Natrinema sp., Natronobacterium sp., Natronorubrum sp., Natronococcus sp. Halomonas sp., Cobetia sp., Paracoccus sp. and mixtures thereof.

[0014] In some instances, the polyhydroxyalkanoate-accumulating bacteria is preferably made up of thermophilic bacteria selected from the group consisting of Chelatococcus thermo stellatus, Caldimonas taiwanesis, Aneurinibacillus sp.Hl, Tepidimonas taiwanensis EMG 22826, Moorella thermoacetica, Schlegelella sp., Kyrpidia spormannii, Moorella thermoautotrophica, Thermits thermophilus , Archaeoglobales sp., Ferroglobus placidus, Geoglobus sp., Geobacillus species, and mixtures thereof.

[0015] In accordance with certain embodiments, the petroleum-derived polymer or partially petroleum-derived polymer includes at least one polymer selected from the group consisting of polyesters, polyolefins, polyamides, polyethylene terephthalate, polystyrene, petroleum-derived diacids, petroleum-derived diols, degradation products of said polymers, and mixtures thereof.

[0016] In some embodiments, the petroleum-derived polymer or partially petroleum- derived polymer, prior to being mixed with the depolymerase enzyme, is preferably madeof polymer particles having an average size Dv(50) from about 0.35 microns to about 1 ,000 microns, wherein the average particle size is determined by laser diffraction using a Malvern Master Sizer 3000 particle size analyzer.

[0017] According to certain embodiments, the depolymerase enzyme is preferably selected from the group consisting of PETasc, MHETasc, alkane hydrolases, lipases, alkane dehydrogenases, mono-oxygenases, di-oxygenases, laccases, peroxidases and / or cutinases and mixtures thereof.

[0018] In some embodiments, the amount of the depolymerase enzyme in the initial aqueous mixture is preferably from about 0.05 percent to about 20 percent of the amount of the initial petroleum-derived polymer or partially petroleum-derived polymer.

[0019] In some instances, the polymerase enzyme is preferably reacted with the initial petroleum-derived polymer or partially petroleum-derived polymer at a temperature of less than 60 °C. More preferably, the polymerase enzyme is reacted with the initial petroleum- derived polymer or partially petroleum-derived polymer at a temperature of less than 50 °C.

[0020] According to certain embodiments, the at least one polyhydroxyalkanoate preferably has a weight average molecular weight from about 300,000 to about 2,000,000, as determined in accordance with ASTM D5296.

[0021] In some embodiments, the at least one polyhydroxyalkanoate preferably includes at least one polyhydroxyalkanoate selected from the group consisting of poly(hydroxybutyrate) (PHB), poly(hydroxyvalerate) (PHV), poly(hydoxyoctanoate) (PHO), poly(hydoxydecanoate) (PHD), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HHx)), poly(3- hydroxybutyratc-co-3-hydroxyvalcratc-co-3-hydroxyhcxanoatc) (P(3HB-co-3HV-co- HHx)), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate-co-3-hydoxyoctanoate) (P(3HB- co-3HHx-co-3HO)), and mixtures thereof.

[0022] In a second aspect, the present disclosure provides a method for forming a polyhydroxyalkanoate. According to one embodiment, the method includes an initial stepof mixing a petroleum-derived polymer or partially petroleum-derived polymer having an initial weight average molecular weight with dcpolymcrasc enzyme -producing bacteria to form an initial aqueous mixture. The amount of the depolymerase enzyme-producing bacteria in the initial aqueous mixture is from about 5 percent to about 50 percent of the amount of the initial petroleum-derived polymer or partially petroleum-derived polymer, by weight.

[0023] The initial petroleum-derived polymer or partially petroleum-derived polymer is reacted with the depolymerase enzyme for at least two hours to produce a second mixture which includes a plurality of polymer degradation products. These polymer degradation products in the second mixture have a final weight average molecular weight which is at least 10 percent less than the initial weight average molecular weight of the initial petroleum-derived polymer or partially petroleum-derived polymer, wherein all weight average molecular weights are determined in accordance with ASTM D5296.

[0024] The method then optionally includes a step of denaturing the depolymerase enzyme and a step of mixing the polymer degradation products with microorganisms which includes polyhydroxyalkanoate-accumulating bacteria. The polymer degradation products and the microorganisms are then fermented at a temperature from about 25 °C to about 60 °C for a period of at least 24 hours so that the microorganisms consume at least a portion of the polymer degradation products and intercellularly synthesize at least one polyhydroxyalkanoate; and

[0025] Finally, the at least one polyhydroxyalkanoate is separated from the microorganisms .

[0026] According to certain embodiments, the initial aqueous mixture preferably also includes at least one additive selected from the group consisting of emulsifiers, glycerol, inorganic salts, carbon feedstocks, acids, bases, and mixtures thereof.

[0027] In some embodiments, the polyhydroxyalkanoate-accumulating bacteria is preferably made up of mesophilic bacteria selected from the group consisting of Cupriavidus sp., Pseudomonas sp., Escherichia sp., Bacillus sp., Lysinibacillus sp., Brevibacillus sp, Phanerochaete chrysoporium, Comamonas sp., Delftia sp., Penicilliumsimplicissimum, Rhodococcus ruber, Ideonella sakaiensis, Staphylococcus sp., Chromobacterium sp., Alcaligenes eutrophus, Ralstonia eutropha, Rhodobacter sphaeroides, Pseudomonas sp., Escherichia coli, Wautersia eutropha, Hydrogenophaga pseudoflava, Sac char ophagus degradans, Azohydromonas lata, Methylobacterium sp., Azotobacter sp., Burkholderia sp., Zobellella denitrificans , Aeromonas sp., Erwinia sp., Marinobacter sp., Azospire sp., Aspergillus eutrophus and mixtures thereof.

[0028] In certain embodiments, the polyhydroxyalkanoate-accumulating bacteria is preferably made up of halophilic bacteria selected from the group consisting of Haloarcula sp., Haloferax sp., Halopiger sp., Haloquadratum sp., Halobacterium sp., Halostagnicola sp., Haloterrigena sp., Halobiforma sp., Halococcus sp., Halorubrum sp., Halalkalicoccus sp., Halogeometricum sp., Halogranum sp., Natrinema sp., Natronobacterium sp., Natronorubrum sp., Natronococcus sp. Halomonas sp., Cobetia sp., Paracoccus sp. and mixtures thereof.

[0029] In some instances, the polyhydroxyalkanoate-accumulating bacteria is preferably made up of thermophilic bacteria selected from the group consisting of Chelatococcus thennostellatus. Caldimonas taiwanesis, Aneurinibacillus sp.Hl, Tepidimonas taiwanensis LMG 22826, Moorella thermoacetica, Schlegelella sp., Kyrpidia spormannii. Moorella thermoautotrophica, Thermus thermophilus, Archaeoglobales sp., Eerroglobus placidus, Geoglobus sp., Geobacillus species, and mixtures thereof.

[0030] In accordance with certain embodiments, the petroleum-derived polymer or partially petroleum-derived polymer includes at least one polymer selected from the group consisting of polyesters, polyolefins, polyamides, polyethylene terephthalate, polystyrene, petroleum-derived diacids, petroleum-derived diols, degradation products of said polymers, and mixtures thereof.

[0031] In some embodiments, the petroleum-derived polymer or partially petroleum- derived polymer, prior to being mixed with the depolymerase enzyme, is preferably made of polymer particles having an average size Dv(50) from about 0.35 microns to about 1 ,000 microns, wherein the average particle size is determined by laser diffraction using a Malvern Master Sizer 3000 particle size analyzer.

[0032] According to certain embodiments, the depolymerase enzyme is preferably selected from the group consisting of PETasc, MHETasc, alkane hydrolases, lipases, alkane dehydrogenases, mono-oxygenases, di-oxygenases, laccases, peroxidases and / or cutinases and mixtures thereof.

[0033] In some embodiments, the amount of the dcpolymcrasc enzyme in the initial aqueous mixture is preferably from about 0.05 percent to about 20 percent of the amount of the initial petroleum-derived polymer or partially petroleum-derived polymer.

[0034] In some instances, the polymerase enzyme is preferably reacted with the initial petroleum-derived polymer or partially petroleum-derived polymer at a temperature of less than 60 °C. More preferably, the polymerase enzyme is reacted with the initial petroleum- derived polymer or partially petroleum-derived polymer at a temperature of less than 50 °C.

[0035] According to certain embodiments, the at least one polyhydroxyalkanoate preferably has a weight average molecular weight from about 300,000 to about 2,000,000, as determined in accordance with ASTM D5296.

[0036] In some embodiments, the at least one polyhydroxyalkanoate preferably includes at least one polyhydroxyalkanoate selected from the group consisting of poly(hydroxybutyrate) (PHB), poly(hydroxyvalerate) (PHV), poly(hydoxyoctanoate) (PHO), poly(hydoxydecanoate) (PHD), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HHx)), poly(3- hydroxybutyratc-co-3-hydroxyvalcratc-co-3-hydroxyhcxanoatc) (P(3HB-co-3HV-co- HHx)), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate-co-3-hydoxyoctanoate) (P(3HB- co-3HHx-co-3HO)), and mixtures thereof.DETAILED DESCRIPTION

[0038] The present disclosure provides a method for forming a polyhydroxyalkanoate by reacting a petroleum-derived polymer or partially petroleum-derived polymer with a depolymerase enzyme to form a plurality of polymer degradation products. These polymer degradation products arc then fermented with microorganisms which include polyhydroxyalkanoate-accumulating bacteria in order to synthesize at least one polyhydroxyalkanoate.

[0039] According to the present disclosure, the petroleum-derived polymer or partially petroleum-derived polymer is mixed with a depolymerase enzyme. Typically, the petroleum-derived polymer or partially petroleum-derived polymer and the depolymerase enzyme are mixed extracellularly in an aqueous mixture within a reactor vessel. In some instances, this initial aqueous mixture may also comprise at least one additive selected from the group consisting of emulsifiers, glycerol, inorganic salts, carbon feedstocks, acids, bases, and mixtures thereof.

[0040] The amount of the depolymerase enzyme in this initial aqueous mixture is typically from about 0.0005 percent to about 50 percent of the amount of the initial petroleum- derived polymer or partially petroleum-derived polymer, by weight. More preferably, the amount of the depolymerase enzyme in the initial aqueous mixture is preferably from about 0.05 percent to about 20 percent of the amount of the initial petroleum-derived polymer or partially petroleum-derived polymer, by weight.

[0041] Alternatively, the depolymerase enzymes may be provided by mixing the petroleum-derived polymer or partially petroleum-derived polymer with bacteria which arc capable of producing the depolymerase enzymes in the initial aqueous mixture. In such instances, the amount of the depolymerase enzyme-producing bacteria in the initial aqueous mixture is from about 5 percent to about 50 percent of the amount of the initial petroleum-derived polymer or partially petroleum-derived polymer, by weight.

[0042] Suitable examples of petroleum-derived polymers or partially petroleum-derived polymer which may be included in the initial aqueous mixture may be selected from the group consisting of polyesters, polyolefins, polyamides, polyethylene terephthalate,polystyrene, petroleum-derived diacids, petroleum-derived diols, degradation products of said polymers, and mixtures thereof. Particularly preferred examples of petroleum-derived polymers or partially petroleum-derived polymer for use in the present method include polyethylene, polypropylene, polytetrafluoroethylene, polybutylene adipate terephthalate, polybutylene succinate, polybutylene succinate adipate, and polystyrene.

[0043] The petroleum-derived polymer or partially petroleum-derived polymer has an initial weight average molecular weight, prior to mixing with the depolymerase enzyme which is typically from about 1000 to about 400,000 Daltons, as determined in accordance with ATSM D5296. More preferably, the initial weight average molecular weight of the petroleum-derived polymer or partially petroleum-derived polymer is from about 2000 to about 200,000 Daltons. Even more preferably, the initial weight average molecular weight of the petroleum-derived polymer or partially petroleum-derived polymer is from about 10,000 to about 150,000 Daltons.

[0044] In some instances, it may be preferred to cut, grind, or otherwise comminute petroleum-derived polymer or partially petroleum-derived polymer into relatively small particles prior to mixing with the depolymerase enzyme. By reducing the size of the polymer particles, the polymer particles are able to react more quickly with the depolymerase enzyme. For instance, in certain embodiments, the petroleum-derived polymer or partially petroleum-derived polymer, prior to being mixed with the depolymerase enzyme, is preferably made of polymer particles having an average size Dv(50) from about 0.35 microns to about 1,000 microns, wherein the average particle size is determined by laser diffraction using a Malvern Master Sizer 3000 particle size analyzer.

[0045] Suitable depolymerase enzymes for use in the process are enzymes which are capable of catalyzing the depolymerization of petroleum-derived polymers or partially petroleum-derived polymer. Examples of suitable enzymes may be selected from the group consisting of PETase, MHETase, alkane hydrolases, lipases, alkane dehydrogenases, mono-oxygenases, di-oxygenases, laccases, peroxidases and / or cutinases and mixtures thereof. Particularly preferred enzymes include PETase, MHETase, and leaf-branch compost cutinase (LLC).

[0046] Upon mixing, the initial petroleum-derived polymer or partially petroleum -derived polymer is reacted with the dcpolymcrasc enzyme for at least two hours to produce a second mixture which includes a plurality of polymer degradation products. The polymerase enzyme is typically reacted with the initial petroleum-derived polymer or partially petroleum-derived polymer at a temperature of less than 60 °C. More preferably, the polymerase enzyme is reacted with the initial petroleum-derived polymer or partially petroleum-derived polymer at a temperature of less than 50 °C.

[0047] The polymer degradation products in the second mixture after this reaction have a final weight average molecular weight which is at least 10 percent less than the initial weight average molecular weight of the initial petroleum-derived polymer or partially petroleum-derived polymer, wherein all weight average molecular weights are determined in accordance with ASTM D5296.

[0048] Following this reaction, the depolymerase enzyme in the second mixture is then optionally denatured. This is typically accomplished by addition of heat, denaturing chemicals, or a change in pH to the mixture.

[0049] After this, the polymer degradation products are then mixed with microorganisms which include polyhydroxyalkanoate-accumulating bacteria. The polymer degradation products and the microorganisms are then fermented at a temperature from about 25 °C to about 60 °C for a period of at least 24 hours so that the microorganisms consume at least a portion of the polymer degradation products and intercellularly synthesize at least one polyhydroxyalkanoate.

[0050] In some instances, the polyhydroxyalkanoatc-accumulating bacteria may comprise bacterial which are mesophilic, halophilic, and / or thermophilic. For example, in certain embodiments, the polyhydroxyalkanoate-accumulating bacteria preferably comprise mesophilic bacteria selected from the group consisting of Cupriavidus sp. , Pseudomonas sp., Escherichia sp., Bacillus sp., Lysinibacillus sp., Brevibacillus sp, Phanerochaete chrysoporium, Comamonas sp., Delftia sp., Penicillium simplicissimum, Rhodococcus ruber, Ideonella sakaiensis, Staphylococcus sp., Chromobacterium sp., Alcaligenes eutrophus, Ralstonia eutropha, Rhodobacter sphaeroides, Pseudomonas sp., Escherichia coli, Wautersia eutropha, Hydrogenophaga pseudoflava, Saccharophagus degradans,Azohydromonas lata, M ethylobacterium sp., Azotobacter sp., Burkholderia sp., Zobellella denitrificans , Aeromonas sp., Erwinia sp., Marinobacter sp., Azospire sp., Aspergillus eutrophus and mixtures thereof.

[0051] In other embodiments, the polyhydroxyalkanoate-accumulating bacteria preferably comprise halophilic bacteria selected from the group consisting of Haloarcula sp., Haloferax sp., Halopiger sp., Haloquadratum sp., Halobacterium sp., Halostagnicola sp., Haloterrigena sp., Halobiforma sp., Halococcus sp., Halorubrum sp., Halalkalicoccus sp., Halogeometricum sp., Halogranum sp., Natrinema sp., Natronobacterium sp., Natronorubrum sp., Natronococcus sp. Halomonas sp., Cobetia sp., Paracoccus sp. and mixtures thereof.

[0052] In still other embodiments, the polyhydroxyalkanoate-accumulating bacteria preferably comprise thermophilic bacteria selected from the group consisting of Chelatococcus thennostellatus, Caldimonas taiwanesis, Aneurinibacillus sp.Hl, Tepidimonas taiwanensis LMG 22826, Moorella thermoacetica, Schlegelella sp., Kyrpidia spormannii, Moorella thermoautotrophica, Thermus thermophilus , Archaeoglobales sp., Ferroglobus placidus, Geoglobus sp., Geobacillus species, and mixtures thereof.

[0053] Once the fermentation is completed, the at least one polyhydroxyalkanoate is finally separated from the microorganisms. This may be accomplished by, for example, lysing the microorganism and separating the PHA from the biomass using centrifugation and thermal or chemical extraction, resulting in PHA isolation. Final steps include washing and drying the PHA.

[0054] The at least one polyhydroxyalkanoatc produced by this process typically has a weight average molecular weight from about 300,000 to about 2,000,000 Daltons, and more preferably from about 300,000 to about 1,400,000 Daltons, as determined in accordance with ASTM D5296.

[0055] In some embodiments, the at least one polyhydroxyalkanoate preferably includes at least one polyhydroxyalkanoate selected from the group consisting of poly(hydroxybutyrate) (PHB), poly(hydroxyvalerate) (PHV), poly(hydoxyoctanoate) (PHO), poly(hydoxydecanoate) (PHD), poly(3-hydroxybutyrate-co-4-hydroxybutyrate)(P(3HB-co-4HB)), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)), poly(3-hydroxybutyratc-co-3-hydroxyhcxanoatc) (P(3HB-co-3HHx)), poly(3- hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (P(3HB-co-3HV-co- HHx)), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate-co-3-hydoxyoctanoate) (P(3HB- co-3HHx-co-3HO)), and mixtures thereof.

[0056] EMBODIMENTS

[0057] The present disclosure is also further illustrated by the following embodiments:

[0058] Embodiment 1. A method for forming a polyhydroxyalkanoate comprising the steps of:

[0059] extracellularly mixing a petroleum-derived polymer or partially petroleum-derived polymer having an initial weight average molecular weight with a depolymerase enzyme to form an initial aqueous mixture, wherein the amount of the depolymerase enzyme in the initial aqueous mixture is from about 0.0005 percent to about 50 percent of the amount of the initial petroleum-derived polymer or partially petroleum-derived polymer, by weight; and

[0060] reacting the initial petroleum-derived polymer or partially petroleum-derived polymer with the depolymerase enzyme for at least two hours to produce a second mixture comprising a plurality of polymer degradation products, wherein the polymer degradation products in the second mixture have a final weight average molecular weight which is at least 10 percent less than the initial weight average molecular weight of the initial petroleum-derived polymer or partially petroleum-derived polymer, wherein all weight average molecular weights are determined in accordance with ASTM D5296;

[0061] denaturing the depolymerase enzyme;

[0062] mixing the polymer degradation products with microorganisms comprising polyhydroxyalkanoate-accumulating bacteria;

[0063] fermenting the polymer degradation products and the microorganisms at a temperature from about 25 °C to about 60 °C for a period of at least 24 hours so that themicroorganisms consume at least a portion of the polymer degradation products and intcrccllularly synthesize at least one polyhydroxyalkanoatc; and

[0064] separating the at least one polyhydroxy alkanoate from the microorganisms.

[0065] Embodiment 2. The method of Embodiment 1, wherein the initial aqueous mixture further comprises at least one additive selected from the group consisting of emulsifiers, glycerol, inorganic salts, carbon feedstocks, acids, bases, and mixtures thereof.

[0066] Embodiment 4. The method of Embodiment 1, wherein the polyhydroxyalkanoate- accumulating bacteria comprises mesophilic bacteria selected from the group consisting of Cupriavidus sp., Pseudomonas sp., Escherichia sp., Bacillus sp., Lysinibacillus sp., Brevibacillus sp, Phanerochaete chrysoporium, Comamonas sp., Delftia sp., Penicillium simplicissimum, Rhodococcus ruber, Ideonella sakaiensis, Staphylococcus sp., Chromobacterium sp., Alcaligenes eutrophus, Ralstonia eutropha, Rhodobacter sphaeroides, Pseudomonas sp., Escherichia coli, Wautersia eutropha, Hydrogenophaga pseudoflava, Saccharophagus degradans, Azohydromonas lata, Methylobacterium sp., Az.otobacter sp., Burkholderia sp., Zobellella denitrificans, Aeromonas sp., Erwinia sp., Marinobacter sp., Azospire sp., Aspergillus eutrophus and mixtures thereof.

[0067] Embodiment 5. The method of Embodiment 1, wherein the polyhydroxyalkanoate- accumulating bacteria comprises halophilic bacteria selected from the group consisting of Haloarcula sp., Haloferax sp., Halopiger sp., Haloquadratum sp., Halobacterium sp., Halostagnicola sp., Haloterrigena sp., Halobiforma sp., Halococcus sp., Halorubrum sp., Halalkalicoccus sp., Halogeometricum sp., Halogranum sp., Natrinema sp., Natronobacterium sp., Natronorubrum sp., Natronococcus sp. Halomonas sp., Cobetia sp., Paracoccus sp. and mixtures thereof.

[0068] Embodiment 6. The method of Embodiment 1, wherein the polyhydroxyalkanoate- accumulating bacteria comprises thermophilic bacteria selected from the group consisting of Chelatococcus thermo stellatus, Caldimonas taiwanesis, Aneurinibacillus sp.Hl, Tepidimonas taiwanensis LMG 22826, Moorella thermoacetica, Schlegelella sp., Kyrpidia spormannii, Moorella thermoautotrophica, Thermits thermophilus, Archaeoglobales sp., Ferroglobus placidus, Geoglobus sp., Geobacillus species, and mixtures thereof.

[0069] Embodiment 7. The method of Embodiment 1, wherein the petroleum-derived polymer or partially petroleum-derived polymer comprises at least one polymer selected from the group consisting of polyesters, polyolefins, polyamides, polyethylene terephthalate, polystyrene, petroleum-derived diacids, petroleum-derived diols, degradation products of said polymers, and mixtures thereof.

[0070] Embodiment 8. The method of Embodiment 1, wherein the petroleum-derived polymer or partially petroleum-derived polymer, prior to mixing with the depolymerase enzyme, comprises polymer particles having an average size Dv(50) from about 0.35 microns to about 1,000 microns, wherein the average particle size is determined by laser diffraction using a Malvern Master Sizer 3000 particle size analyzer.

[0071] Embodiment 9. The method of Embodiment 1, wherein the depolymerase enzyme is selected from the group consisting of PETase, MHETase, alkane hydrolases, lipases, alkane dehydrogenases, mono-oxygenases, di-oxygenases, laccases, peroxidases and / or cutinases and mixtures thereof.

[0072] Embodiment 10. The method of Embodiment 1, wherein the amount of the depolymerase enzyme in the initial aqueous mixture is from about 0.05 percent to about 20 percent of the amount of the initial petroleum-derived polymer or partially petroleum- derived polymer.

[0073] Embodiment 11. The method of Embodiment 1 , wherein the depolymerase enzyme is reacted with the initial petroleum-derived polymer or partially petroleum-derived polymer at a temperature of less than 60 °C.

[0074] Embodiment 12. The method of Embodiment 1, wherein the depolymerase enzyme is reacted with the initial petroleum-derived polymer or partially petroleum-derived polymer at a temperature of less than 50 °C.

[0075] Embodiment 13. The method of Embodiment 1, wherein the at least polyhydroxyalkanoate has a weight average molecular weight from about 300,000 to about 2,000,000, as determined in accordance with ASTM D5296.

[0076] Embodiment 14. The method of Embodiment 1 , wherein the at least one polyhydroxyalkanoatc comprises at least one polyhydroxyalkanoatc selected from the group consisting of poly(hydroxybutyrate) (PHB), poly(hydroxyvalerate) (PHV), poly(hydoxyoctanoate) (PHO), poly(hydoxydecanoate) (PHD), poly(3-hydroxybutyrate- co-4-hydroxybutyrate) (P(3HB-co-4HB)), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HHx)), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (P(3HB-co-3HV- co-HHx)), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate-co-3-hydoxyoctanoate) (P(3HB-co-3HHx-co-3HO)), and mixtures thereof.

[0077] Embodiment 15. A method for forming a polyhydroxy alkanoate comprising the steps of:

[0078] mixing a petroleum-derived polymer or partially petroleum-derived polymer having an initial weight average molecular weight with depolymerase enzyme-producing bacteria to form an initial aqueous mixture, wherein the amount of the depolymerase enzyme-producing bacteria in the initial aqueous mixture is from about 5 percent to about 50 percent of the amount of the initial petroleum-derived polymer or partially petroleum- derived polymer, by weight; and

[0079] reacting the initial petroleum-derived polymer or partially petroleum-derived polymer with the depolymerase enzyme produced by the bacteria for at least two hours to produce a second mixture comprising a plurality of polymer degradation products, wherein the polymer degradation products in the second mixture have a final weight average molecular weight which is at least 10 percent less than the initial weight average molecular weight of the initial petroleum-derived polymer or partially petroleum-derived polymer, wherein all weight average molecular weights are determined in accordance with ASTM D5296;

[0080] optionally, denaturing the depolymerase enzyme;

[0081] mixing the polymer degradation products with microorganisms comprising polyhydroxyalkanoate-accumulating bacteria;

[0082] fermenting the polymer degradation products and the microorganisms at a temperature from about 25 °C to about 60 °C for a period of at least 24 hours so that the microorganisms consume at least a portion of the polymer degradation products and intercellularly synthesize at least one polyhydroxyalkanoate; and

[0083] separating the at least one polyhydroxy alkanoate from the microorganisms.

[0084] Embodiment 17. The method of Embodiment 1, wherein the initial aqueous mixture further comprises at least one additive selected from the group consisting of emulsifiers, glycerol, inorganic salts, carbon feedstocks, acids, bases, and mixtures thereof.

[0085] Embodiment 18. The method of Embodiment 1, wherein the polyhydroxyalkanoate-accumulating bacteria comprises mesophilic bacteria selected from the group consisting of Cupriavidus sp., Pseudomonas sp., Escherichia sp., Bacillus sp., Lysinibacillus sp., Brevibacillus sp, Phanerochaete chrysoporium, Comamonas sp., Delftia sp., Penicillium simplicissimum, Rhodococcus ruber, Ideonella sakaiensis, Staphylococcus sp., Chromobacterium sp., Alcaligenes eutrophus, Ralstonia eutropha, Rhodobacter sphaeroides, Pseudomonas sp., Escherichia coli, Wautersia eutropha, Hydrogenophaga pseudoflava, Saccharophagus degradans, Azohydromonas lata, Methylobacterium sp., Azotobacter sp., Burkholderia sp., Zobellella denitrificans, Aeromonas sp., Erwinia sp., Marinobacter sp., Azospire sp. , Aspergillus eutrophus and mixtures thereof.

[0086] Embodiment 19. The method of Embodiment 1, wherein the polyhydroxyalkanoate-accumulating bacteria comprises halophilic bacteria selected from the group consisting of Haloarcula sp., Haloferax sp., Halopiger sp., Haloquadratum sp., Halobacterium sp., Halostagnicola sp., Haloterrigena sp., Halobiforma sp., Halococcus sp., Halorubrum sp., Halalkalicoccus sp., Halogeometricum sp., Halogranum sp., Natrinema sp., Natronobacterium sp., Natronorubrum sp., Natronococcus sp. Halomonas sp. , Cobetia sp. , Paracoccus sp. and mixtures thereof.

[0087] Embodiment 20. The method of Embodiment 1, wherein the polyhydroxyalkanoate-accumulating bacteria comprises thermophilic bacteria selected from the group consisting of Chelatococcus thermostellatus , Caldimonas taiwanesis, Aneurinibacillus sp.Hl, Tepidimonas taiwanensis LMG 22826, Moorella thermoacetica,Schlegelella sp., Kyrpidia spormannii, Moorella therrnoautotrophica, Thermus thermophilus, Archaeoglobales sp., Ferroglobus placidus, Geoglobus sp., Geobacillus species, and mixtures thereof.

[0088] Embodiment 21. The method of Embodiment 1 , wherein the petroleum-derived or partially petroleum-derived polymer polymer comprises at least one polymer selected from the group consisting of polyesters, polyolefins, polyamides, polyethylene terephthalate, polystyrene, petroleum-derived diacids, petroleum-derived diols, degradation products of said polymers, and mixtures thereof.

[0089] Embodiment 22. The method of Embodiment 1, wherein the petroleum-derived polymer or partially petroleum-derived polymer, prior to mixing with the depolymerase enzyme, comprises polymer particles having an average size Dv(50) from about 0.35 microns to about 1000 microns, wherein the average particle size is determined by laser diffraction using a Malvern Master Sizer 3000 particle size analyzer.

[0090] Embodiment 23. The method of Embodiment 1, wherein the depolymerase enzyme produced by the bacteria is selected from the group consisting of PETase, MHETase, alkane hydrolases, lipases, alkane dehydrogenases, mono-oxygenases, di -oxygenases, laccases, peroxidases and / or cutinases and mixtures thereof.

[0091] Embodiment 24. The method of Embodiment 1, wherein the depolymerase enzyme is reacted with the initial petroleum-derived polymer or partially petroleum-derived polymer at a temperature of less than 60 °C.

[0092] Embodiment 25. The method of Embodiment 1, wherein the depolymerase enzyme is reacted with the initial petroleum-derived polymer or partially petroleum-derived polymer at a temperature of less than 50 °C.

[0093] Embodiment 26. The method of Embodiment 1, wherein the at least one polyhydroxyalkanoate has a weight average molecular weight from about 300,000 to about 2,000,000, as determined in accordance with ASTM D5296.

[0094] Embodiment 27. The method of Embodiment 1, wherein the at least one polyhydroxyalkanoate comprises at least polyhydroxyalkanoate selected from the groupconsisting of poly(hydroxybutyrate) (PHB), poly(hydroxyvalerate) (PHV), poly(hydoxyoctanoatc) (PHO), poly(hydoxydccanoatc) (PHD), poly(3-hydroxybutyratc- co-4-hydroxybutyrate) (P(3HB-co-4HB)), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HHx)), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (P(3HB-co-3HV- co-HHx)), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate-co-3-hydoxyoctanoate) (P(3HB-co-3HHx-co-3HO)), and mixtures thereof.

[0095] The foregoing description of preferred embodiments for this disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments are chosen and described in an effort to provide the best illustrations of the principles of the disclosure and its practical application and to thereby enable one of ordinary skill in the art to utilize the disclosure in various embodiments and with various modifications as are suited to the particular use contemplated.

Claims

('[ AIMSClaim 1. A method for forming a polyhydroxyalkanoatc comprising the steps of: extracellularly mixing a petroleum-derived polymer or partially petroleum-derived polymer having an initial weight average molecular weight with a depolymerase enzyme to form an initial aqueous mixture, wherein the amount of the depolymerase enzyme in the initial aqueous mixture is from about 0.0005 percent to about 50 percent of the amount of the initial petroleum-derived polymer or partially petroleum-derived polymer, by weight; and reacting the initial petroleum-derived polymer or partially petroleum-derived polymer with the depolymerase enzyme for at least two hours to produce a second mixture comprising a plurality of polymer degradation products, wherein the polymer degradation products in the second mixture have a final weight average molecular weight which is at least 10 percent less than the initial weight average molecular weight of the initial petroleum-derived polymer or partially petroleum-derived polymer, wherein all weight average molecular weights are determined in accordance with ASTM D5296; denaturing the depolymerase enzyme; mixing the polymer degradation products with microorganisms comprising polyhydroxyalkanoate-accumulating bacteria; fermenting the polymer degradation products and the microorganisms at a temperature from about 25 °C to about 60 °C for a period of at least 24 hours so that the microorganisms consume at least a portion of the polymer degradation products and intercellularly synthesize at least one polyhydroxyalkanoate; and separating the at least one polyhydroxyalkanoate from the microorganisms.Claim 2. The method of Claim 1, wherein the initial aqueous mixture further comprises at least one additive selected from the group consisting of emulsifiers, glycerol, inorganic salts, carbon feedstocks, acids, bases, and mixtures thereof.Claim 4. The method of Claim 1, wherein the polyhydroxyalkanoate-accumulating bacteria comprises mesophilic bacteria selected from the group consisting of Cupriavidus sp., Pseudomonas sp., Escherichia sp., Bacillus sp., Lysinibacillus sp., Brevibacillus sp, Phanerochaete chrysoporium, Comamonas sp., Delftia sp., Penicillium simplicissimum, Rhodococcus ruber, Ideonella sakaiensis, Staphylococcus sp., Chromobacterium sp.,Alcaligenes eutrophus, Ralstonia eutropha, Rhodobacter sphaeroides, Pseudomonas sp., Escherichia coli, Wautersia eutropha, Hydro genophaga pseudoflava, Saccharophagus degradans, Azohydromonas lata, Methylobacterium sp. , Azotobacter sp. , Burkholderia sp. , Zobellella denitrificans, Aeromonas sp., Erwinia sp., Marinobacter sp., Azospire sp., Aspergillus eutrophus and mixtures thereof.Claim 5. The method of Claim 1, wherein the polyhydroxyalkanoate-accumulating bacteria comprises halophilic bacteria selected from the group consisting of Haloarcula sp., Haloferax sp., Halopiger sp., Haloquadratum sp., Halobacterium sp., Halostagnicola sp., Haloterrigena sp., Halobiforma sp., Halococcus sp., Halorubrum sp., Halalkalicoccus sp., Halogeometricum sp., Halogranum sp., Natrinema sp., Natronobacterium sp., Natronorubrum sp., Natronococcus sp. Halomonas sp., Cobetia sp., Paracoccus sp. and mixtures thereof.Claim 6. The method of Claim 1, wherein the polyhydroxyalkanoate-accumulating bacteria comprises thermophilic bacteria selected from the group consisting of Chelatococcus thermostellatus, Caldimonas taiwanesis, Aneurinibacillus sp.Hl, Tepidimonas taiwanensis LMG 22826, Moorella thermoacetica, Schlegelella sp. , Kyrpidia spormannii, Moorella thermoautotrophica, Thermus thermophilus , Archaeoglobales sp., Ferroglobus placidus, Geoglobus sp., Geobacillus species, and mixtures thereof.Claim 7. The method of Claim 1, wherein the petroleum-derived polymer or partially petroleum-derived polymer comprises at least one polymer selected from the group consisting of polyesters, polyolefins, polyamides, polyethylene terephthalate, polystyrene, petroleum-derived diacids, petroleum-derived diols, degradation products of said polymers, and mixtures thereof.Claim 8. The method of Claim 1, wherein the petroleum-derived polymer or partially petroleum-derived polymer, prior to mixing with the depolymerase enzyme, comprises polymer particles having an average size Dv(50) from about 0.35 microns to about 1,000 microns, wherein the average particle size is determined by laser diffraction using a Malvern Master Sizer 3000 particle size analyzer.Claim 9. The method of Claim 1, wherein the depolymerase enzyme is selected from the group consisting of PETase, MHETase, alkane hydrolases, lipases, alkanedehydrogenases, mono-oxygenases, di-oxygenases, laccases, peroxidases and / or cutinases and mixtures thereof.Claim 10. The method of Claim 1, wherein the amount of the depolymerase enzyme in the initial aqueous mixture is from about 0.05 percent to about 20 percent of the amount of the initial petroleum-derived polymer or partially petroleum-derived polymer.Claim 11. The method of Claim 1, wherein the depolymerase enzyme is reacted with the initial petroleum-derived polymer or partially petroleum-derived polymer at a temperature of less than 60 °C.Claim 12. The method of Claim 1, wherein the depolymerase enzyme is reacted with the initial petroleum-derived polymer or partially petroleum-derived polymer at a temperature of less than 50 °C.Claim 13. The method of Claim 1, wherein the at least polyhydroxyalkanoate has a weight average molecular weight from about 300,000 to about 2,000,000, as determined in accordance with ASTM D5296.Claim 14. The method of Claim 1, wherein the at least one polyhydroxyalkanoate comprises at least one polyhydroxyalkanoate selected from the group consisting of poly(hydroxybutyrate) (PHB), poly(hydroxyvalerate) (PHV), poly(hydoxyoctanoate) (PHO), poly(hydoxydecanoate) (PHD), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HHx)), poly(3- hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (P(3HB-co-3HV-co- HHx)), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate-co-3-hydoxyoctanoate) (P(3HB- co-3HHx-co-3HO)), and mixtures thereof.Claim 15. A method for forming a polyhydroxyalkanoate comprising the steps of: mixing a petroleum-derived polymer or partially petroleum-derived polymer having an initial weight average molecular weight with depolymerase enzyme-producing bacteria to form an initial aqueous mixture, wherein the amount of the depolymerase enzyme-producing bacteria in the initial aqueous mixture is from about 5 percent to about 50 percent of the amount of the initial petroleum-derived polymer or partially petroleum- derived polymer, by weight; andreacting the initial petroleum-derived polymer or partially petroleum-derived polymer with the dcpolymcrasc enzyme produced by the bacteria for at least two hours to produce a second mixture comprising a plurality of polymer degradation products, wherein the polymer degradation products in the second mixture have a final weight average molecular weight which is at least 10 percent less than the initial weight average molecular weight of the initial petroleum-derived polymer or partially petroleum-derived polymer, wherein all weight average molecular weights are determined in accordance with ASTM D5296; optionally, denaturing the depolymerase enzyme; mixing the polymer degradation products with microorganisms comprising polyhydroxyalkanoate-accumulating bacteria; fermenting the polymer degradation products and the microorganisms at a temperature from about 25 °C to about 60 °C for a period of at least 24 hours so that the microorganisms consume at least a portion of the polymer degradation products and intercellularly synthesize at least one polyhydroxyalkanoate; and separating the at least one polyhydroxy alkanoate from the microorganisms.Claim 17. The method of Claim 1, wherein the initial aqueous mixture further comprises at least one additive selected from the group consisting of emulsifiers, glycerol, inorganic salts, carbon feedstocks, acids, bases, and mixtures thereof.Claim 18. The method of Claim 1, wherein the polyhydroxy alkanoate- accumulating bacteria comprises mesophilic bacteria selected from the group consisting of Cupriavidus sp., Pseudomonas sp., Escherichia sp., Bacillus sp., Lysinibacillus sp., Brevibacillus sp, Phanerochaete chrysoporium, Comamonas sp., Delftia sp., Penicillium simplicissimum, Rhodococcus ruber, Ideonella sakaiensis, Staphylococcus sp., Chromobacterium sp., Alcaligenes eutrophus, Ralstonia eutropha, Rhodobacter sphaeroides, Pseudomonas sp., Escherichia coli, Wautersia eutropha, Hydrogenophaga pseudoflava, Saccharophagus degradans, Azohydromonas lata, Melhylobacterium sp., Azotobacter sp., Burkholderia sp., Zobellella denitrificans, Aeromonas sp., Erwinia sp., Mari obacter sp., Azo spire sp., Aspergillus eutrophus and mixtures thereof.Claim 19. The method of Claim 1, wherein the polyhydroxyalkanoate- accumulating bacteria comprises halophilic bacteria selected from the group consisting ofHaloarcula sp., Haloferax sp., Halopiger sp., Haloquadratum sp., Halobacterium sp., Halostagnicola sp., Haloterrigena sp., Halobiforma sp., Halococcus sp., Halorubrum sp., Halalkalicoccus sp., Halogeometricum sp., Halogranum sp., Natrinema sp., Natronobacterium sp., Natronorubrum sp., Natronococcus sp. Halomonas sp., Cobetia sp., Paracoccus sp. and mixtures thereof.Claim 20. The method of Claim 1, wherein the polyhydro xyalkanoate- accumulating bacteria comprises thermophilic bacteria selected from the group consisting of Chelatococcus thermostellatus , Caldimonas taiwanesis, Aneurinibacillus sp.Hl, Tepidimonas taiwanensis LMG 22826, Moorella thermoacetica, Schlegelella sp., Kyrpidia spormannii, Moorella thermoautotrophica, Thermits thermophilus, Archaeoglobales sp., Ferroglobus placidus, Geoglobus sp., Geobacillus species, and mixtures thereof.Claim 21. The method of Claim 1, wherein the petroleum-derived polymer or partially petroleum-derived polymer comprises at least one polymer selected from the group consisting of polyolefins, polyamides, polyethylene terephthalate, polystyrene, petroleum-derived diacids, petroleum-derived diols, degradation products of said polymers, and mixtures thereof.Claim 22. The method of Claim 1, wherein the petroleum-derived polymer or partially petroleum-derived polymer, prior to mixing with the depolymerase enzyme, comprises polymer particles having an average size Dv(50) from about 0.35 microns to about 1000 microns, wherein the average particle size is determined by laser diffraction using a Malvern Master Sizer 3000 particle size analyzer.Claim 23. The method of Claim 1, wherein the depolymerase enzyme produced by the bacteria is selected from the group consisting of PETase, MHETase, alkane hydrolases, lipases, alkane dehydrogenases, mono-oxygenases, di -oxygenases, laccases, peroxidases and / or cutinases and mixtures thereof.Claim 24. The method of Claim 1, wherein the depolymerase enzyme is reacted with the initial petroleum-derived polymer or partially petroleum-derived polymer at a temperature of less than 60 °C.Claim 25. The method of Claim 1, wherein the depolymerase enzyme is reacted with the initial petroleum-derived polymer or partially petroleum-derived polymer at a temperature of less than 50 °C.Claim 26. The method of Claim 1 , wherein the at least polyhydroxyalkanoate has a weight average molecular weight from about 300,000 to about 2,000,000, as determined in accordance with ASTM D5296.Claim 27. The method of Claim 1, wherein the at least one poly hydroxy alkanoate comprises at least one polyhydroxyalkanoate selected from the group consisting of poly(hydroxybutyrate) (PHB), poly(hydroxyvalerate) (PHV), poly(hydoxyoctanoate) (PHO), poly(hydoxydecanoate) (PHD), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)), poly(3-hydroxybutyrate-co-3-hydroxy valerate) (P(3HB-co-3HV)), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HHx)), poly(3- hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (P(3HB-co-3HV-co- HHx)), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate-co-3-hydoxyoctanoate) (P(3HB- co-3HHx-co-3HO)), and mixtures thereof.