Optimization of polyhydroxybutyrate production by marine Bacillus megaterium MSBN04 under solid state culture

A marine sponge-associated bacterium Bacillus megaterium MSBN04 was used for the production of polyhydroxybutyrate (PHB) under solid state culture (SSC). A central composite design (CCD) was employed to optimize the production medium and to find out the interactive effects of four independent variables, viz. tapioca industry waste, palm jaggery, horse gram flour and trace element solution on PHB production. The maximum yield of PHB 8.637 mg g−1 of substrate (tapioca industry waste) was achieved from biomass 15.203 mg g−1 of substrate, using statistically optimized medium. The horse gram flour (nitrogen source) and trace element solution were found to be critical control factors for PHB synthesis. The 1H NMR analysis revealed that the polymer was a PHB monomer. PHB obtained from this study having high molecular weight (6.7 × 105 Da) with low polydispersity index (PDI) value (1.71) and produced PHB was used to synthesize PHB polymeric nanoparticles using solvent displacement approach. Therefore, B. megaterium MSBN04 is an ideal candidate that can be exploited biotechnologically for the commercial production of PHB under solid state culture.