Identification of bacteria producing a thermophilic lipase with positional non-specificity and characterization of the lipase

Abstract

A bacterial isolate producing lipase, named S31, was isolated from soil and identified as a strain ofBurkholderia cepacia. S31 produced high activity of lipase which reached a maximum of 226.1 u/ml by fermenting at 30 °C for 60 h under the induction of olive oil. After purification, the lipase showed a single band of about 35 kDa in SDS-PAGE. The optimum temperature of the lipase was 70 °C and the optimum pH was 9.0. S31 lipase was stable at 40-70 °C and pH 0.5–10.0, as well as in several organic solvents, such as methanol, n-hexane, n-butanol, toluene and ethyl acetate. The presence of some metal ions (Ca2+, Mn2+, K+, Na+ and Mg2+) could activate the enzyme whereas Fe2+ and Cu2+ were found to be inhibitory. The lipase could cleave all of the three ester bonds of triglycerides. We conclude that S31 lipase is an alkaline lipase with a variety of highly desirable characteristics for research and industrial application.