Characterization of Lipases from a Vegetable Oil Contaminated Soil Fungal Isolates.

Abstract

Lipases are enzymes that hydrolyse lipids to produce free fatty acids and glycerol. Fungi were cultured on sabouraud dextrose agar (SDA) plates and identified using microscopic techniques. Screening for lipase producers was carried out on SDA media supplemented with 3 % olive oil at ambient temperature. M. pusillus, M. canis, A. fumigatus, Yeast and T. mentagrophytes were found to produce lipases in different amounts with Yeast and M. canis being the highest producers, they were further characterised for this reason. Lipase production was carried out using submerged fermentation. Both Yeast and M. canis produced lipases maximally at 72 h. Optimum pH and temperature of activity for the lipases from Yeast were determined to be 5 and 35 oC respectively whereas, those from M. canis were 6 and 40 oC correspondingly. Yeast and M. canis lipases had preference for olive oil than vegetable and palm oils and both enzymes were activated by K+, Mg2+ and Ca2+ and inhibited by Fe3+, Hg2+ and Co2+. The lipase enzyme from Yeast had Vmax of 0.0006 U/mL/Sec, Km of 0.4242 mM and Kcat of 0.0004 S-1 while that from M. canis had corresponding Vmax, Km and Kcat of 0.0001 U/mL/Sec, 3.2287 mM and 0.0001 S-1.