Chandani N., Mazumder P. B., Bhattacharjee A.
Abstract: Polyhydroxybutyrate (PHB) is a biodegradable polymer produced by many bacteria. It can be used as an alternative to petroleum-based commercial plastics as they can be easily degraded by the soil microorganisms. The present work focuses on screening a potential bacterium for PHB production. In this study, 50 bacterial colonies from the soil samples were isolated and screened for PHB production. They were grown in basally-defined M9 medium (DM9 medium) and screened for biosynthesis of PHB using Sudan Black B stain. 20 were found to be able to produce PHB and among them, isolate 3 showed highest productions of 1.0g/l PHB from 1.92g/l DCW (dry cell weight). Isolate 3 was characterized as Bacillus tequilensis NCS-3 based on 16S rRNA gene sequence. This isolate was selected to optimize its culture conditions using different carbon sources, nitrogen sources, pH and temperatures. After optimization, the isolate yielded maximum amount of 1.75g/l PHB from 2.01g/l DCW at pH 6 and incubation temperature of 300C using fructose and tryptone as carbon and nitrogen sources. PHB production increases from 52 % to 87 % after optimization, which indicates that Bacillus tequilensis NCS-3 was a potent PHB producer.
Keywords: Polyhydroxybutyrate PHB, Biopolymer, Bacillus tequilensis NCS-3, 16S rRNA, DM9 medium