Production of Polyhydroxybutyrate Using Bacterial Strains of Escherichia Coli and Bacillus Subtilis: A Comparison

Polyhydroxybutyrate (PHB), a polyhydroxyalkanoate (PHA), is of interest as bio-derived plastics. PHB is obtained from renewables and is compostable and biodegradable. An extensive literature review indicated that a number of microorganisms produce PHB for the purpose of energy generation. The source of these micro-organisms was investigated. Garden soil was collected and screened for PHB producing bacteria. Several unidentified bacterial colonies were isolated using serial dilution method. Each bacterial colony was maintained in slants and liquid cultures. A lab strain of E.coli was cultured in a 5-L stirred tank bioreactor and kinetic studies were performed till it reached stationary phase at 17 hours. The maximum biomass obtained was 3.7 g/l. Similarly sample of B.subtilis was taken and bacterial colonies were isolated. Slant streaks and liquid cultures were maintained. Same procedure was carried out for B.subtilis. The maximum biomass obtained in case of B.subtilis was. The polyhydroxybutyrate produced in both cases were analyzed and compared. B.subtilis produced more amount of polyhydroxybutyrate as compared to E.coli