LIPOLYTIC ACTIVITY OF MICROORGANISMS ASSOCIATED WITH SOMEPALM OIL PROCESSING COTTAGE INDUSTRIES IN EKITI- STATE, NIGERIA

Abstract

Palm oil industry is currently a world leader in the supply of oils and fats which constitutes one of the major sectors of the highest economic importance in Nigeria. The importance of palm oil in the country is due to the versatility of applications of their by-products, such as cooking oil, margarines, soaps, detergents, cosmetics, lubricants, biofuels and electric power, among many others. This study investigates the lipolytic activity of microorganisms associated with palm oil milleffluent in cottage industries.Effluent samples were taken from a depth of 10-15 cm in six different locations within Ekiti State, Nigeria. Microorganisms were isolated from the effluents and identified using standard microbiological techniques and molecular characterization. The microbial isolates were screened for lipase production using modified mineral\ salt medium in submerged fermentation. Lipase production by the isolateswas assessed by halo zone of clearance on nutrient agar plates after incubation at 37oC for 24 hours.The physiochemical characterizations of the isolates were carried out and the process parameters (nitrogen, carbon, temperature and pH) were optimized. The proximate contents (moisture, carbohydrate, crude protein, fat, ash) in all the samples were determined. Partial purification of crude extract from P. aeruginosa was carried out by ammonium sulphate precipitation and dialysis. The strains of molecularly identified bacteria were Pseudomonas aeruginosa AE016853.1;P. syringae CP019871.1and P. putida JQ782512.1. The fungal isolates wereAspergillus niger; Microsporium fulvum; Mucor sp.; Penicillium sp. and Aspergillus flavus. The pH of the inoculum ranged from 6.23 to 6.01 oil and grease contents ranged from 149.6 to 114.2 mg/l while the biochemical oxygen demand ranging from 42760 to 33800 mg/l. The chemical oxygen demandranged from 1.9 to 1.8 mg/l. P. aeruginosaexhibited highest enzyme activity ranging from 75.33 to 22.44 μmol/min/ml and the least by B. cereus.The proximate analyses of the palm oil mill effluents revealed a significant difference P<0.05) in the distribution of proximate content in samples used.Ijan Ekiti had the highest moisture content of POME (8.45%) while the least (6.12 %) was obtained from Ago Aduloju, there was variation in the ash content in which Sajowa had highest percentage ash content of 17.34% and Ijan had the least (13.55%). The highest crude protein (17.52%) was recorded from sample obtained in Ijan Ekiti while highest lipid content (10.12%) was obtained from Aba Medi. The least soluble carbohydratewas obtained from Saw mill (23.28%) with highest value (27.89%) obtained from College road.Fermentation medium supplemented with ammonium nitrate had the highest lipase activity (2.81 μmol/min) while the medium supplemented withpotassium nitrate recorded had the least lipase activities of (1.50 μmol/min). Highest lipase activity of 2.68 μmol/min) from P. aeruginosa was recorded from a medium supplemented with palm oil while the medium supplemented with goya oil had least lipase activity 2.31 μmol/min.The lipase activity increased with increase in incubation temperature at 50oC with relative activity of 99.9 % before it declined to 15 % at 80oC. From this study, the microorganisms (P.aeruginosa,P. syringae and P. putida) isolated from the selected palm oil processing sites display high potential of lipase production. The lipase produced from the Pseudomonas aeruginosa exhibited high lypolytic activities.It can therefore, be a biodegradable agent for industrial applications especially in the waste treatment especially of waste rich in oil and fats. Thus, lipase may act as a biodegradable agent for industrial applications.