Production, optimization and characterization of polyhydroxybutyrate, a biodegradable plastic by Bacillusspp.

Poly-β-hydroxybutyrate (PHB) is the intracellular lipid reserve accumulated by many bacteria. The most potent terrestrial bacterium Bacillus cereusSE-1 showed more PHB accumulating cells (22.1 and 40% after 48 and 72 h) than that of the marine Bacillussp. CS-605 (5 and 33% after 48 and 72 h). Both the isolates harbored phbBgene and the characteristics C=O peak was observed in the extracted PHB by Fourier transformed infrared spectroscopy analysis. Maltose was found to be the most suitable carbon source for the accumulation of PHB in B. cereusSE-1. The extracted PHB sample from B. cereusSE-1 was blended with a thermoplastic starch (TS) and an increased thermoplasticity and decreased crystallinity were observed after blending in comparison to the standard PHB. The melting temperature (Tm), melting enthalpy (∆Hf), and crystallinity (Xc) of the blended PHB sample were found to be 109.4 °C, 64.58 J/g, and 44.23%, respectively.