Abstract

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Petroleum derived plastics constitute environmental problem because they are not biodegradable. Alternative substrates for manufacture of biodegradable plastics are necessary to safeguard the environment. Some bacterial genera produce Poly-p hydroxybutyrate (PHB), under adverse nutrient conditions, which serve as alternatives for petroleum derived plastics. Azotobacterspis associated with its biosynthesis. Media suitable for growth of Azotobactervinelandiiior the accumulation of PHB are needed. In an effort to find out these facts, Azotobacter was isolated from rhizopheric soil of maize crop at Uli in Anambra State, Nigeria, by a selective media. Morphological characteristics were creamy beige colonies, Gram stain indicated negative rods. Biochemical tests were positive for catalase, oxidase, citrate, indole, sucrose, lactose, and hydrogen sulphide production, confirming the isolate to be Azotobactervinelandiiby Bergey's criteria. Growth of the isolate in acetate medium containing casitone as nitrogen source did not yield PHB. Combination of glucose and ammonium acetate medium containing castione gave the best yield of PHB per milliliter and per milligram of glucose consumed. Cell dry weight was 24.6% increase in GAAM and 22.50% in ACM. Treatment with sodium hypochlorite for 1 hour at 60°C lysed the cells of A. vinelandii. Addition of ethanol and acetone removed cell lipids and other molecules. Treatment with chloroform extracted PHB. Media combining glucose, ammonium acetate and casitone are suitable for A. vinelandii biosynthesis of PHB while chloroform extracts it.

Keywords: Azotobactervinelandii, chloroform extraction, poly-B-hydroxybutyrate biosynthesis, media selection