Polyhydroxybutyrate Production by Stenotrophomonas and Exiguobacterium Using Renewable Carbon Source

Aims: The basic purpose of this study was to evaluate the potential of these bacterial strains to use arbon rich waste materials as nutrients and use them to produce cost effective polyhydroxybutyrate (PHB).

Study Design: Basic phenotypic and genotypic study of screening bacteria for low-cost PHB production.

Place and Duration of Study: Identified bacterial strains were taken from lab collection of Department of Microbiology and Molecular Genetics. This study was conducted between 2011-2012.

Methodology: Carbon rich waste materials as nutrients and use them to produce cost effective amount of PHB. Two indigenous bacterial strains Stenotrophomonas and Exiguobacterium were used in this study. The potato starch and waste water with minimum treatment were used as carbon sources and compared with glucose. The Fourier transform infrared spectroscopy was used to confirm the presence of the polyhydroxybutyrate.

Results: The percentage PHB was 10.2%, 8.6%, 48.02% when glucose, potato starch and waste water was used as sole carbon source strain Exiguobacterium respectively. While for Stenotrophomonas the higher rate accumulation rate for PHB was 11.7%, 10.4% and 36.4% using glucose, potato starch and waste water as carbon source respectively. The Fourier transform infrared spectroscopy confirmed the presence of C=O in the PHB material extracted from the biomass. The genetic basis for the PHB production was also confirmed by sequencing phaC gene for the selected strains.

Conclusion: This study directs that environmental bacterial strains use many renewable carbon sources like waste materials to accumulate the PHB could be very cost effective. Stenotrophomonas and Exiguabacterium producing PHB using organic waste material nonetheless still there is a prerequisite to do more research on their production optimization and genetics.