Polyhydroxyalkanoate production and related processes

Abstract

Embodiments of the invention relate generally to processes for the production and processing of polyhydroxyalkanoates (PHA) from carbon sources. In several embodiments, PHAs are produced at high efficiencies from carbon-containing gases through the utilization of a regenerative polymerization system.

1 .- 18 . (canceled) 
     
     
         19 . A process for producing polyhydroxyalkanoate (PHA) by a culture of microorganisms, the process comprising:
 (a) providing a culture of two or more strains of microorganisms comprising a first strain of methanotrophic microorganisms capable of metabolizing methane to synthesize PHA and a second strain of microorganisms capable of metabolizing a PHA-reduced biomass to synthesize PHA;   (b) providing a culture medium comprising at least one nutrient, methane, and a PHA-reduced biomass;   (c) exposing said culture to said culture medium;   (d) subjecting said culture to a growth period causing said first strain to use said methane to reproduce and said second strain to use said PHA-reduced biomass to reproduce; and   (e) subjecting said grown culture to a polymerization period by reducing the concentration of at least one of said nutrients thereby causing said first strain to use said methane to synthesize PHA and said second strain to use said PHA-reduced biomass to synthesize PHA.   
     
     
         20 . The process of  claim 19 , further comprising the step of removing a portion of said culture following said polymerization period. 
     
     
         21 . The process of  claim 20 , further comprising the step of extracting said PHA from said removed culture thereby producing a PHA extract and a PHA-reduced biomass. 
     
     
         22 . The process of  claim 19 , wherein said methanotrophic microorganism further metabolizes gases, including carbon dioxide, volatile organic compounds, air and/or oxygen. 
     
     
         23 . The process of  claim 21 , further comprising the step of returning said PHA-reduced biomass to said culture medium of  claim 19 , step (b) to serve as a carbon source for said second strain of microorganisms. 
     
     
         24 . The process of  claim 19 , wherein said culture of microorganisms comprise a mixed culture of microorganisms comprising carbon-dioxide utilizing microorganisms, heterotrophic microorganisms, autotrophic microorganisms, cyanobacteria, biomass-utilizing microorganisms, methanogenic microorganisms, aerobic microorganisms, anaerobic microorganisms, acidogenic microorganisms, and/or acetogenic microorganisms. 
     
     
         25 . The process of  claim 23 , wherein said PHA-reduced biomass is metabolized as assimilable sources of carbon and converted into said PHA. 
     
     
         26 . The process of  claim 25 , wherein said carbon within said PHA-reduced biomass is metabolized by said second culture to produce carbon dioxide and/or methane whereby said carbon dioxide and/or said methane is further metabolized by said first strain of microorganisms capable of metabolizing methane in the production of said PHA. 
     
     
         27 . The process of  claim 21 , wherein extracting said PHA from said removed culture comprises mixing said removed culture with an extraction agent or mechanism selected from the group consisting of solvents, solvent washing, chemical treatment, microwave treatment, simple or fractional distillation, supercritical carbon dioxide, heat, enzymes, surfactants, acids, bases, hypochlorite, peroxides, bleaches, ozone, EDTA, and/or a combinations thereof. 
     
     
         28 . The process of  claim 27 , wherein said solvent is selected from the group consisting of methylene chloride, acetone, ethanol, methanol, ketones, alcohol, chloroform, dichloroethane, water, carbon dioxide, and/or a combinations thereof. 
     
     
         29 . The process of  claim 27 , wherein said mechanism is selected from the group consisting of sonication, homogenization, distillation, spray drying, hypochlorite non-PHA dissolution, protonic non-PHA dissolution, non-PHA dissolution, enzymatic treatment, and/or freeze drying. 
     
     
         30 . The process of  claim 19 , further comprising the step of introducing a light during said growth period. 
     
     
         31 . The process of  claim 30 , wherein said light is introduced using light emitting device to influence the metabolism of said culture. 
     
     
         32 . The process of  claim 30 , wherein said light is emitted by a device that is charged by inserting the two leads of a 115V AC power source into said culture medium. 
     
     
         33 . The process of  claim 19 , wherein said methane is derived from one or more sources from the group consisting of landfills, wastewater treatment plants, power production facilities or equipment, agricultural digesters, oil refineries, natural gas refineries, natural gas streams, cement production facilities, and/or anaerobic organic waste digesters. 
     
     
         34 . A process for polyhydroxyalkanoate (PHA) production by a culture of microorganisms, the process comprising:
 (a) fermenting a culture of at least two strains of microorganisms comprising a culture medium, a first strain of microorganism capable of metabolizing a carbon-containing gas, a second strain of microorganism capable of metabolizing a reduced biomass, and at least one nutrient;   (b) exposing said fermenting culture of microorganisms to an excess supply of carbon-containing gas throughout said fermentation step;   (c) subjecting said fermenting culture of microorganisms to a growth period causing said culture of fermenting microorganisms to reproduce;   (d) subjecting said fermenting culture of microorganisms to a polymerization period by reducing the concentration of at least one of said nutrients thereby causing said reproduced culture capable of synthesizing PHA to synthesize PHA;   (e) repeatedly cycling said culture of microorganisms between said growth period and said polymerization period until the desired quantity of intracellular PHA is produced by those microorganisms capable of producing PHA thereby producing a PHA-containing biomass;   (f) removing a portion of said microorganisms following step (e) to harvest said PHA to create a reduced biomass;   (g) returning said reduced biomass produced in step (f) to the culture of step (a), wherein reducing the concentration of said one or more nutrients in step (c) and supplying an excess quantity of carbon-containing gas further causes said first and second strain of microorganism to synthesize PHA from said carbon-containing gas and said reduced biomass respectively; and   (h) repeating steps (a)-(h) at least two times, to increase the yield of PHA produced using only said carbon containing gas and said reduced biomass as a carbon source.   
     
     
         35 . The method of  claim 34 , wherein said culturing is performed under non-sterile conditions. 
     
     
         36 . The method of  claim 34 , wherein said PHA concentrations are least 80% of total dry cell weight of said first strain of microorganism. 
     
     
         37 . The method of  claim 34 , wherein said additional nutrient comprises at least one of the nutrients selected from the group consisting of aluminum, boron, calcium, carbon, carbon dioxide, cobalt, iron, magnesium, molybdenum, nitrogen, oxygen, phosphorus, potassium, sodium, and zinc. 
     
     
         38 . The method of  claim 34 , wherein said first strain of microorganism capable of metabolizing a carbon-containing gas comprises methanotrophic microorganisms of a genus selected from a group consisting of:  Methylosinus, Methylocystis, Methylococcus, Methylobacterium , and  Pseudomonas.    
     
     
         39 . The method of  claim 34 , wherein at least one of said additional nutrient comprises dissolved oxygen and wherein the method further comprises increasing the concentration of dissolved oxygen in said culture media to preferentially select for methanotrophic microorganisms exhibiting reduced pigmentation. 
     
     
         40 . The method of  claim 34 , further comprising purifying said extracted PHA.