[Production of polyhydroxyalkanoates by a mixed culture]

The feasibility of using a mixed culture of A. chroococcum G-3 and B. megaterium G-6 in the production of polyhydroxyalkanoates has been studied. The optimal conditions for the mixed culture were established. After the G-3 strain was incubated alone for 24 - 28 hours, the broth was inoculated with 15% (v/v) of the G-6 culture. 0.5% peptone and 0.5% NH4NO3 were added to the mixture. The mixed culture was proceed to 42 - 46 h. Final dry cell weight was up to 32 g/L and the content of PHA was up to 80%. Combined with the nutrient supplement, the dry cell weight increased to 53 g/L and the content of PHA increased to 42g/L. The conversion of sucrose to PHA is 0.32. The mixed culture solved the problems caused by the increase in viscosity, poor mass transfer, low supplemental sucrose amounts.