Purification and characterization of an extracellular lipase from Trichosporon sp. and its application in enrichment of omega-3 polyunsaturated fatty acids

Abstract

Lipase catalysis has become the most promising technique for enrichment of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) due to its mild and green conditions. In this study, Trichosporon sp. F1-2 was newly isolated from oil-contaminated sludge, and its extracellular lipase was purified using ammonium sulfate precipitation and DEAE-Sepharose chromatography. The molecular weight of the lipase was estimated to be 32.6 kDa. The optimal temperature and pH for lipase activity were 50 °C and 8.0, respectively, and the optimal storage conditions were found to be temperatures below 45 °C and pH 7.0–9.0. The lipase did not require metal ions as cofactors and was significantly inhibited by Zn2+. It was stable in various organic solvents with different log P values, and n-hexane, toluene, dichloromethane, diethyl ether and glycerol even enhanced its activity. It had sn-1,3 regioselectivity and the highest activity towards a medium-chain fatty acid (C8) ester. This study demonstrated the lipase has good potential as a catalyst in enrichment of EPA and DHA in fish oil. The content of EPA and DHA reached 22.9 and 25.4 mol%, respectively, using 100 U of the lipase within 24 h, and the enrichment efficiency of DHA was higher than that of EPA.