TITLE OF MANUSCRIPT: ENHANCEMENT OF LIPOLYTIC CHARACTERISTICS OF A PALM-OIL MILL EFFLUENT-SOURCED KODAMAEA OHMERI PL2

Abstract

The hydrolysis of long-chain triglycerides and fats is catalyzed by lipases, important enzymes which have essential biotechnological, medical, and industrial roles. Fungi were isolated from palm-oil mill wastes and screened for their lipid-hydrolyzing potentials. Lipase production and activity characteristics were determined using different substrates. Sixteen, out of the 75 fungi isolated, exhibited lipolytic characteristics. Yeast isolate PL2 gave the highest zone of hydrolysis (44.5 mm) and was identified as Kodamaea ohmeri. This yeast was cultured under diverse media conditions for lipase production and the enzyme produced under each physicochemical condition was determined spectrophotometrically. The optimum parameters for lipase production (1% Tween-80, Ca2+, peptone, 37°C and pH 6) were used to produce lipase which was further purified through (NH4)2SO4 precipitation, membrane dialysis and gel chromatography. The activity of the partially purified lipase increased progressively with each purification stage. The lipase had optimum activity at 50oC and was alkalophilic with peak pH for enzymatic hydrolysis at 8.0. The lipase was supported by 0.5% concentrations of SDS and Triton X-100 (129.9 and 129.4%, respectively), and a 100-fold activity increase with 0.5% Tween-80. Lipase activity was augmented by Manganese and calcium ions (10 mM) but inhibited by NH4+, Fe3+ and Na+. The use of Tween-80 resulted in increased enzyme yield as well as better enzyme characteristics compared to other substrates. The knowledge obtained in this study may be harnessed for commercialization of Kodamaea ohmeri lipase.