Optimization Of Geotrichum Sp. SYBC WU-3 Fermentation For Lipase Production And The Enzyme Characterization

Lipases are important enzymes universally applied in industries; it is significant to screen new lipase resources and to characterize novel lipases for specific application.A strain of lipase producing microbial was isolated from nature. It was morphologically idntified as Geotrichum .sp and termed as Geotrichum sp. SYBC WU-3.The effect of inducing agents and suefactants on the lipase production of Geotrichum sp. SYBC WU-3 was investigated. The results showed that olive oil, nuts composite oil, Tween-20, Tween-80, and TritoonX-100 could promote lipase production by Geotrichum sp. SYBC WU-3, when nut complex oil and TritoonX-100 or olive oil and TritoonX-100 was added to the medium, a new isozyme named as LIP-1 could be induced, the constitutive lipas of Geotrichum sp. SYBC WU-3 was termed as LIP-2.The optimum medium for the yield of lipase was that containing peptone 5 g/L, NaH2PO4 3g/L, nuts oil 250 mL/L, Polyoxyethylene polyglycol ether 25 mL/L. The strain was cultivated at the temperature of 30℃for 72 h. The enzyme activity under the optimal condition was 3.2 folds of that under the condition before optimization.Isozyme LIP-1 and LIP-2 was purified by DEAE-32 chromatography, Sephadex G-100 gel filtration and two-phase extraction. LIP-1 and LIP-2 was purified 15.6 and 22 folds respctively. Their recovery was 11.15 %and 17.9 % respectively.Both LIP-1 and LIP-2 was cold-adapted alkaline lipase. Their optimal pH in 50 mmol/L pH 7.0 Tris-HCl buffer are 9.5. Both of them showed high lipolytic activity from pH 3.0 to 9.0. The optimal catalytic temperature of LIP-1 and LIP-2 was 20℃and 15℃respectively. LIP-1 was labile at 50℃, LIP-2 was labile at 40℃. LIP-1 had stronger ability to hydrolyte long chain fatty acid esters and LIP-2 had high hydrolysis ability to hydrolyte short chain fatty acid esters.