MAINTAINING A CONTROLLED RESIDUAL GROWTH CAPACITY INCREASES THE PRODUCTION OF POLYHYDROXYALKANOATE COPOLYMERS BY ALCALIGENES-EUTROPHUS

The manner in which copolymer poly(HB-co-HV) production was influenced by different methods of limiting cell proliferation during the produc tion phase was examined. Polymer production was significantly improved in fermentation strategies in which some growth was maintained, eithe r by linear or exponential nitrogen source feeding as compared to cult ures in which nitrogen supply was totally interrupted. Improved volume tric productivities were obtained in cultures fed with NH4OH and the p roportion of 3HV incorporated was approximately twofold higher in thes e cultures. These performance improvements were due to higher specific rates of glucose and propionate consumption in cultures in which true growth capacity was maintained.