Abstract:A strain, Pseudomonas sp. X-2-45, with high and stable lipolytical activity was screened by continuously subculturing a lipase-producing bacterium P. sp. LP-1 in culture medium containing Jatropha oil as a sole carbon source. Its hydrolytic activity was 29.79 U/mL, which was increased by 288% as compared to that of parent strain. Furthermore, the growth and lipase synthesis of X-2-45, its catalytic ability to hydrolyze vegetable oils, as well as ester synthesis between fatty acids and organic alcohols were studied. Results showed that rates of bacterial growth and lipase synthesis were significantly raised. Bacterial biomass and lipase activity reached the highest level after 30 h of incubation. Moreover, growth stationary period was prolonged and lipase produced exhibited good stability in culture media during incubation period. Hydrolytic activity of P. sp. X-2-45 lipase toward Jatropha oil was increased by 378% as compared to parent strain, suggesting that acclimation to Jatropha oil was an effective approach for improving substrate selectivity of lipase. Finally, results of ester synthesis catalyzed by P. sp. X-2-45 lipase indicated that this lipase could catalyze esterification reactions between lauric acid and n-butanol, n-octanol, 1-dodecanol or glycerol, palmitic acid or stearic acid and methanol, n-octanol, 1-dodecanol or glycerol, oleic acid and methanol, n-butanol, n-octanol, 1-dodecanol or glycerol.
