ISOLATION, IDENTIFICATION AND CHARACTERIZATION OF POLYHYDROXYBUTYRATE PRODUCING Bacillus flexus

Dwindling crude oil reservoirs and increasing environmental and societal concerns over harmful effects of synthetic plastics have increased the pressure on development of sustainable and environmentally friendly biopolymers like Polyhydroxybutyrate (PHB). Present work aimed at isolating and characterizing PHB producing bacteria from soil. Isolation from rhizospheric soil samples yielded 85 isolates, which were screened for PHB production by Sudan Black B followed by Nile Blue A staining procedures. Overall, 21.18% isolates tested positive for PHB production. The polymer production by the isolates was found to vary from 0.011- 0.186 g/L of the dry cell weight. The highest PHB yield was observed in R8, which was characterized for its morphological and biochemical properties. Based on its 16S rRNA gene sequences, isolate was identified as Bacillus flexus. The ability of the organism to produce protease, amylase and lipase indicated possibility of using various low cost agro-industrial, food and dairy wastes as carbon substrates for cost-effective PHB production. Its hydrolytic potential coupled with resistance to heavy metals and antibiotics can be explored for PHB production using waste water.