NOVELTY - Method (M1) for enhancing polyhydroxyalkanoate (PHA) generation in methanotrophic culture, involves (a) contacting a culture of methanotrophic microorganisms with a medium comprising copper, one or more of additional nutrients and carbon-containing gas metabolized by the culture, (b) incubating culture in the medium to cause growth of the culture, and (c) inducing selection pressure in the culture to transform the culture into a culture that generates PHA preferentially through pMMO.    USE - The method (M1) is useful for enhancing PHA generation in methanotrophic culture. The method (M2) is useful for converting carbon-containing material into PHA. The method (M3) is useful for controlling functional characteristics of PHA produced by methanotrophic culture. The method (M4) is useful for modifying functional characteristics of PHA. The method (M5) is useful for improving the functional characteristics of PHA polymer. The method (M6) is useful for synthesizing PHA in biomass material. The process is useful for extracting PHA from PHA-containing biomass slurry (all claimed). The PHAs are thermoplastic polyesters useful as carbon and energy storage vehicles in microorganisms, and alternatives to fossil fuel-based plastics e.g. polypropylene, polyethylene, and polystyrene.    ADVANTAGE - The PHAs are biodegradable in both aerobic and anaerobic conditions and biocompatible with mammalian tissues, is environmentally-friendly as compared to petrochemical-based plastics, and can be produced from carbon-containing gases with improved energy yield, as compared to sugar-based PHA production methodologies in a cost-effective manner as carbon input costs are reduced, carbon to PHA yield is increased, volume of chemicals required for PHA production are reduced, and/or energy to PHA yield is increased.    DETAILED DESCRIPTION - Method (M1) for enhancing polyhydroxyalkanoate (PHA) generation in methanotrophic culture by reducing copper concentration to effect particulate methane monooxygenase (pMMO) production, involves (a) contacting a culture of methanotrophic microorganisms with a medium comprising copper, one or more of additional nutrients and carbon-containing gas metabolized by the culture, (b) incubating culture in the medium to cause growth of the culture, and (c) inducing selection pressure in the culture to transform the culture into a culture that generates PHA preferentially through pMMO. The step (c) involves (i) reducing the concentration of copper in the medium to cause production of soluble methane monooxygenase (sMMO) and/or particulate methane monooxygenase by the culture, where the concentration of copper causes the production of sMMO in some methanotrophic microorganisms, (ii) reducing the concentration of one or more nutrients in the medium to cause the culture to generate PHA from carbon-containing gas using sMMO or pMMO, where PHA is generated by pMMO at a greater rate as compared to sMMO, (iii) returning the culture to growth conditions of step (b), where microorganisms having higher intracellular concentrations of pMMO and PHA grows at a greater rate as compared to those with lower intracellular pMMO and PHA concentrations, and (iv) repeating steps (ii) and (iii) such that the repetitions selectively favors growth of microorganisms that produce PHA through pMMO, thus facilitating the pMMO-mediated production of PHA at reduced copper concentration, and resulting in a culture comprising essentially only microorganisms which uses pMMO to produce PHA. INDEPENDENT CLAIMS are included for the following:    (1) method (M2) for converting carbon-containing material into PHA;    (2) method (M3) for controlling functional characteristics of PHA produced by methanotrophic culture exposed to methane and one or more nonmethane materials that influence metabolism of the culture;    (3) method (M4) for modifying functional characteristics of PHA;    (4) method (M5) for improving the functional characteristics of PHA polymer through melting and cooling of PHA polymer in the presence of dual-miscible biomass agent and a second polymer;    (5) method (M6) for synthesizing a PHA in a biomass material; and    (6) process for extracting a PHA from PHA-containing biomass slurry comprising PHA, nonPHA biomass, and a liquid, involves (a) (i) controlling the pressure and temperature of the liquid to cause nonPHA biomass to become soluble in the liquid, and (ii) reducing the amount of liquid in the slurry, or (b) (i) controlling the pressure and temperature of the liquid to cause nonPHA biomass to become soluble in the liquid, and (ii) modifying the concentration of the liquid in biomass slurry.