Production, purification and characterization of an extracellular lipase from Mucor hiemalis f. hiemalis

Mucor hiemalis f. hiemalis is a major contaminant of cameroonian palm fruit and produces an inducible extracellular lipase in batch fermentation. Rape oil was the best inducer for enzyme production, with the highest activity being achieved after 6 days of incubation. The enzyme was purified 2200-fol d by ultrafiltration, ammonium sulfate fractionation, Sephadex G75 chromato graphy, Q-Sepharose chromatography, and Sephacryl S-200 chromatography. The purified enzyme showed a prominent polypeptide band in polyacrylamide gel electrophoresis, associated with esterase activity according to activity st aining. Molecular weight of the lipase was estimated to be 49 kDa using gel filtration on Sephadex G75, and 49 kDa by sodium dodecyl sulfate polyacryl amide gel electrophoresis. The enzyme was identified as a glycoprotein with pi of 4.6. The N-terminal amino acid sequence data (19 residues) and the a mino acid composition were determined. The optimum pH and temperature for a ctivity of the enzyme were 7.0 and 40 degrees C, respectively. The lipase w as stable in the pH range of 4-9 and at 45 degrees C for 15 min. It hydroly zed both synthetic and natural triglycerides with optimal activities record ed on tricaprylin and rape oil, respectively. Ca2+, Mg2+, Co2+, Mn2+, and N a+-enhanced lipase activity, whereas Fe2+, Cu2+ Ba2+, and surfactants-such as taurocholic acid, triton X-100, and Tween 20-strongly reduced lipase act ivity. The enzyme activity was not affected by EDTA (ethylenediaminetetraac etic acid disodium dihydrate), PMSF (phenylmethylsulfonylfluoride), (p-chlo romercuribenzoic), and Benzamidine. (C) 1999 Elsevier Science Inc. All righ ts reserved.