Isolation of Polyhydroxyalkanoates (PHAs) producing bacteria from hot spring

The increasing awareness on the negative environmental impact of using petroleum-based plastics has driven industries to explore efficient biodegradable polymers sources for production of bioplastic. Polyhydroxyalkanoates (PHAs) is one of the potential biodegradable polymers to replace petroleum-based plastic and it can be produced from renewable carbon sources by microorganisms. It is synthesized and accumulated as intracellular granules in some bacteria. In this study, polyhydroxyalkanoates (PHAs) producing bacteria were successfully isolated from sediment collected from Jeli Hot Spring. Isolation process had been carried out by using Minimal Salt Medium (MSM) agar supplemented with excess glucose as a carbon source. Potential polyhydroxyalkanoates (PHAs) producing bacteria were screened by using Nile blue staining plate assay. Out of 144 isolates, 12 bacterial isolates were selected which showed strong orange fluorescence on Minimal Salt Medium (MSM) agar plates supplemented with Nile blue when examined under UV light (365nm). The potential PHAs producing bacteria were then identified by morphological characterization and biochemical analysis. Gram positive rod shape bacteria B75 and B87 were identified as Corynebacterium kutsceri meanwhile Gram negative rod shape bacteria A4, Al2, A50, A68, B2, B13, B22, B31, B73 and C3 showed affiliation to Citrobacter sp., Enterobacter sp., Erwinia sp., Klebsiella sp., Proteus sp., Salmonella sp., Serratia sp., Shigella sp., and Yersinia sp. After the Nile blue smear staining, it was found that isolate B87 and C3 showed bright orange fluorescence when observed under a fluorescence microscope at 460 nm excitation wavelengths which indicated the presence of PHA granules in their cells. This strongly verified that isolate B87 and C3 are potential PHAs producing bacteria.