Polyhydroxybutyrate Accumulation in Bacillus megaterium and Optimization of Process Parameters Using Response Surface Methodology

The accumulation of polyhydroxybutyrate of Bacillus megaterium is growth associated and significantly dependent on carbon sources. In the present investigation B. megaterium strain isolated from soil was studied for PHB production in fructose minimal media. The PHB production was found to be growth associated. The polymer production by the strain was found to vary from 24 to 48 % content (w/w) of the dry cell weight. Box Bohn design was used to study the interactive effect of four variables on cell growth and PHB production. The optimized medium conditions with the constrain to maximize cell growth and PHB content were glucose 4.32 g/L, Mannitol 4.52 g/L and Na succinate 3.45 g/L and PHB yield 1.38 g/L amounting to 49 % of dry cell weight which is more than 1.8 folds the basal medium. The polymer production by the strain was found to vary from 12.18 to 57.2 % content (w/w) of the dry cell weight.