Bioconversion of glycerol to Polyhdroxylalkanoate by halophilic bacteria isolated from mangrove soil samples

Abstract

Polyhydroxyalkanoate (PHA) is a group of biodegradable polymer, synthesized by many microorganisms. PHA provide a good fully degradable alternative to petrochemical plastics. One of the major bottlenecks in the commercial application of PHA is their high price as compared to the conventional petroleum-based plastic materials. A potential solution for low-cost PHA production is to utilize glycerol (byproduct of biodiesel production) as carbon source. In this study, we isolated seventeen bacteria strains, which were able to synthesize PHA from glycerol. Among them, three strains named VK32, VK56 and VK72 were chosen for further study. They are moderately halophilic and neutrophilic bacteria, able to metabolize different nitrogen sources. Highest PH A content of 61 wt% was obtained by strain VK75 after 30 h cultivation in flask using KNO3 as nitrogen source. Maximum cell dry weight (CDW) of 6 g/1 was obtained by strain VK75 after 30 h cultivation in bioreactor, however, the PHA content was low (19 wt%). Further studies are being carted out to optimize conditions for both cell growth and PHA accumulation by the three selected strains.