Purification and biochemical characterization of a halotolerant Staphylococcus sp. extracellular lipase

We have isolated a lipolytic halotolerant bacterium, designated as CJ3, that was identified as a Staphylococcus sp. Culture conditions were optimized and the highest extracellular lipase production amounting to 5U/ml was achieved after 24h of cultivation. The extracellular lipase was purified 24-fold by ammonium sulfate precipitation and a Sephacryl S-200 chromatography, and its molecular mass was found to be around 38kDa, as revealed by SDS-PAGE and gel filtration. The lipase substrate specificity was investigated using short (tributyrin) and long (olive oil) chain triglyceride substrates. The lipase was inhibited by submicellar concentrations of Triton X-100, and maximum specific activities were found to be 802U/mg on tributyrin and 260U/mg on olive oil at pH 8.0 and 45°C. The lipase was fairly stable in the pH range from 6.0 to 9.0, and about 69% of its activity was retained after incubation at 45°C for 60min. The enzyme showed a high tolerance to a wide range of salt concentration and a good stability in organic solvents, especially in long-chain alcohols.