Purification and Some Characteristics of Extracellular Lipase from Fusarium oxysporum f.sp.lini

Abstract

An extracellular lipase was isolated from a culture filtrate of Fusarium oxysporum f.sp. lini SUF 402 by hydrophobic chromatography. Purity of the preparation was 38-fold and recovery yield was 32%. The molecular mass of the isolated enzyme was 30 kDa. The lipase had a sugar chain, and the N-terminal amino acid was modified. The optimun pH at 37°C was 7.0. The enzyme had higher activity toward p-nitrophenyl esters with long and middle chain fatty acids (C₈-C₁₈) than with a short chain fatty acid (C₄). The enzyme was not inhibited by phenylmethylsulfonyl fluoride or 2-mercaptoethanol. In the case of the lipase, both the hydrolysis rate of tristearin and final concentration of fatty acid content were higher than those of triolein. The lipase was examined with respect to its ability of concentrating the n-3 polyunsaturated fatty acid (n-3 PUFA) content of partially hydrolyzed glycerides (TG and DG) obtained from two kinds of fish oil (cod liver oil and refined sardine oil). The lipase gave increases in n-3 PUFA contents as the hydrolysis progressed. The lipase concentrated only docosahexaenoic acid with little increase in icosapentaenoic acid. Maximal total n-3 PUFA contents were about 30% in both fish oils.