Production and characterization of a thermostable bioplastic (Poly-s-hydroxybutyrate) from bacillus cereus NRRL-b-3711

The poly-β-hydroxybutyrate (phb) is a thermostable and biocompatible polyester produced by several bacteria under unbalanced nutritional conditions. among gram-positive bacteria,which are not well exploited for phb production on industrial scale,bacillus appears to be a prospective candidate due to its excellent biopolymer yield and less rigorous fermentation conditions. batch culture fermentation was carried out for phb production. the bacillus cereus nrrl-b-3711 was the most efficient producer of phb out of five bacillus species. the optimized production was achieved with 2% glucose,37°c,ph value of 8 and ammonium sulfate (2.5 g/l) as a nitrogen source. carbon to nitrogen ratio of 10 significantly affects the phb accumulation. the selected specie was able to accumulate phb up to 56% (14.2 }0.07 g/l) on dry cell weight basis after optimization. this corresponds to a 1.87 folds increase in the production. the optical microscopy showed extremely flat surface of bioplastic thin film indicating the brittle failure of phb under tensile loading. the ftir analysis revealed c=o and –ch groups,with thermal properties e.g. tg; 2°c,tc; 54°c,tm;162°c and % crystallinity of 51.3 by differential scanning calorimeter (dsc),thus confirming the presence of phb bioplastic and enhancing its industrial applications. the results surpassed those reported in the literature for phb production. © 2016,pakistan botanical society. all rights reserved.