Oil Degradation Using a Photosynthetic Bacterium Rhodobacter sphaeroides S

Abstract

Oil degradation in synthetic sewage wastewater was investigated using a photosynthetic bacterium, Rhodobacter sphaeroides S (S strain). When a pure culture of S strain was prepared with glutamate-malate medium (GM medium) containing a salad oil, about 60 % of the oil was degraded under aerobic-dark conditions at 6 days, while oil degradation was relatively small under anaerobic-light conditions. Lipase hydryzed tri-glycerides to glycerol and fatty acids were observed extracellularly in the aerobic-dark culture. Lipase was produced when the S strain grew up with favorable substrates such as glutamate-malate and glucose in the medium. The lipase activity was quite lower than that of Pseudmonus and Bacillus lipase activities. High cell density enhanced oil degradation rather than lipase production in the liquid. S strain well utilized C₁₂ to C₁₈ fatty acids and glycerol as carbon sources respectively.