Characterization of an extracellular alkaline lipase from Pseudomonas mendocina M-37

A strain of Pseudomonas mendocina producing extracellular lipase was isolated from soil. The bacterium accumulates lipase in culture fluid when grown aerobically at 30 degrees C for 24 h in a medium composed of olive oil (1%) as substrate. Pseudomonas mendocina lipase was optimally active at pH 9.0, temperature of 50 degrees C and was found to be stable between pH 7.0-11.0. The lipase was inhibited by detergents such as SDS and Tween-80. The enzyme was stable in various organic solvents tested with maximum stability in chloroform followed by toluene and exhibited 1-3 regiospecificity for hydrolytic reaction. This lipase was capable of hydrolyzing a variety of lipidic substrates and is mainly active towards synthetic triglycerides and fatty acid esters that possess a butyryl group. Metal ions like Mg2+, Ca2+ and Na+ stimulated lipase activity, whereas, Cu2+, Mn2+ and Hg2+ ions caused inhibition.