Potential of dumpsite bacterial isolate in producing polyhydroxybutyrate under stress prone environment

Abstract

Different bacterial species from soil samples of waste dumpsites were isolated and screened for their ability to synthesize polyhydroxybutyrate (PHB). Out of 86 bacterial cultures isolated, 26 isolates showed the presence of lipid granules PHB. Based on high polymer production, 4 potential bacterial isolates were identified by morphological, physiological and 16S rDNA sequencing. Their nucleotide sequences were submitted in the GenBank database under accession numbers KT907042, KT907043, KT907045 and KT907047. As biomass production is analogous to PHB production, cultural parameters like carbon, nitrogen, pH and temperature were optimized for maximum production of polymer by a potential bacterium Bacillus pumilus K8. Growth kinetics of B. pumilus K8 was analyzed and found that it grows at a rate 0.112 gh^-1L^-1 of the production medium. It could achieve maximum production of 72.93% of PHB at the rate of 0.013 gg^-1 of biomass h^-1 with polymer concentration of 5.04 gL^-1 using mannitol, yeast extract, pH 7 and temperature 35°C, respectively as favourable cultural parameters. phbC gene, mainly responsible for PHB production was amplified by PCR and this genotypically confirms PHB production by the bacterial isolates. Bacillus pumilus K8 may be exploited for further industrial production of biopolymer.