Optimisation of Lipases from Fungi Associated with Palm Oil Mill Soils

Lipases are industrially significant enzymes applied in food processing, detergents, pharmaceuticals, cosmetics, and biodiesel manufacture. Palm oil mill effluent (POME), though nutrient- rich and supportive of microbial growth, is also a major pollutant of the environment. Exploring lipolytic fungi from such soils provides a dual benefit of waste management and enzyme generation. Soil samples from palm oil mills in Eyekanse via Owode-Yewa, Yewa South Local Government Area of Ogun State were analysed for fungal diversity and lipase enzyme optimisation. Isolates were obtained through serial dilution on mineral salts agar and screened for lipase activity on tributyrin agar. Promising strains including LFA1 A. niger, LFA2 R. arrhizus, LFA3 A. flavus, LFB7 T. virens, LFC9 T. asperellum, LFC10 A. terreus and LFC12 A. tamarii were cultured in submerged fermentation, using a lipase optimising medium enriched with mineral salts and yeast extract at 30°C for 96 hrs and crude lipase was recovered from the supernatant by centrifugation. Enzyme output was determined spectrophotometrically, while cultural and nutritional parameters were optimised using a one-variable-at-a-time approach. Out of sixteen isolates recovered, seven showed distinct lipase activity. Maximum enzyme levels were obtained at pH 8.0, 45oC, inoculum size 3.5 ml, 48 hrs incubation, and 160 rpm agitation. Palm oil served as the most suitable substrate, xylose supported highest yield as carbon source, while peptone and potassium nitrate proved effective nitrogen supplements. Sodium dodecyl sulphate enhanced enzyme activity. These findings offered valuable insights for optimising conditions to maximise lipase enzyme yield.