Isolation, optimization and production of biopolymer (poly 3-hydroxy butyrate) from marine bacteria

The synthetic polymer plastics become an integral part of contemporary life. Excess use of plastics and indiscriminate dumping of it in soil and water is polluting the environment and other living organisms. To overcome this problem, the production and applications of eco-friendly biodegradable products (such as bioplastics) from microbes are becoming inevitable from the last decade and also good alternatives of synthetic polymers. Keeping this point in mind the present study aimed at isolating and identifying the poly 3- hydroxybutyrate (PHB) producing bacteria from marine sources that can be effectively utilized for the synthesis of bioplastics. For isolation of poly 3-hydroxybutyrate producing bacteria, spread plate technique was followed using E2 mineral medium. After incubation, based on the morphological characteristics 32 strains were isolated and identified from the sand dunes plants of rhizosphere vegetation of Chennai coast. While staining with Sudan Black, six strains viz., AMET 5103, AMET 5111, AMET 5113, AMET 5121, AMET 5124 and AMET 5128 were identified as poly 3-hydroxybutyrate producing bacterial strains. Based on the dry weight of total biopolymer content, the strain AMET 5111 showed the maximum accumulation and was selected for optimizing at different pH, temperature, salinity, carbon and nitrogen source, incubation period and peak time of poly 3-hydroxybutyrate accumulation. Based on the biochemical tests, the strain AMET 5111 was found to be Pseudomonas spp. The optimum pH, temperature and salinity were found to be 7.0, 30°C and 5%. The peak time of poly 3-hydroxybutyrate accumulation was found to be 36hrs. The best carbon and nitrogen sources were found to be sucrose and (NH4)2HPO4. The selected strain was massively cultured using the optimized media and poly 3-hydroxybutyrate was extracted by solvent extraction