Study On Alkaline Lipase

By screening with Rhodarnine B plate method, two strains which had high ability to produce lipase were obtained. One is bacteria called Alcaligenes sp, the other is epiphyte named Penicillium expansum.The fermentation parameters of Alcaligenes sp were studied in shaking flask, including carbon sources , nitrogen sources, nutrition salts, cultivate temperature, initial pH value and surface active agent, etc. The fermentation results in 3L fermentor indicated that aeration and stirring speed had obviously influence on the synthesis of lipase by Alcaligenes sp. The optimal aeration and stirring speed were O.Swm and 400rpm respectively, with which the alkaline lipase activity could reach 225IU/ml.The compositions of medium and culture conditions for Penicillium expansum were also studied in shaking flasks, the alkaline lipase activity was 700 lU/ml, under the optimal medium and culture conditions. The results in 3L fermentor showed the 62 in the medium was fairly important for Penicillium expansum to synthesize lipase.Alcaligenes sp lipase and Penicillium expansum lipase were stable under pH 8.0-10.0 and pH 7.0-9.5, respectively, and both Upases had high activity at pH 9.0-9.5. This property showed both lipases were alkaline Upases and had a good application potential in detergent industry. Alcaligenes sp lipase was stable under 55 癈, with the optimal reaction temperature 40癈. The another lipase was 50癈 and 30-35癈, respectively. Ca2+, Mg2+ were activators and Cu2+,Fe2+ were inhibitors for both alkaline lipase. Na+ was the activator for Penicillium expansum lipase and inhibitor for other lipase.Alkaline lipase produced by microorganism had high economical value. The enzyme preparations had not been manufactured in our country until now. The research in this dissertation was meaningful both in theoretical research and practical application.