Abstract

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Lipases (triacylglycerol acylhydrolases, EC3.1.1.3) are water-soluble enzymes that catalyze the hydrolysis(and synthesis) of ester bonds formed from acyl glycerol and long-chain fatty acids at lipid-water interface. Palm oil mill effluents have been reported to be rich in lipolytic bacteria, thus this work aimed at production, characterization and purification of lipase by bacteria isolated from Palm oil mill effluent and its dumpsites soil. From the serially diluted soil and palm oil mill effluent samples, fifteen(15) bacterial isolates were selected based on the zones of clearance (qualitative screening)on selective agar based medium. They were further screened quantitatively for their lipolyticactivities using titrimetric method. Five bacterial isolates showing high lipase activity were selected and identified based on their morphological, biochemical and physiological characteristics as Bacillus subtilis, Staphylococcus aureus, Bacillus sp., Serratiamarcescens and Pseudomonas aeruginosa.The enzyme exhibited maximum activity at incubation temperature of 45°C at 48hr incubation time and agitation rate of 150rpm. Also, pH 7.0 to 7.5 was found to be best for lipase activity. The lipase produced retained stability up to pH 10 and temperature of 70⁰C. Highest stability of the enzyme was observed with Ca2+and least with Mn2+ metal ions.The total protein content, enzyme activity and specific activity of the enzymes reduced with each purification step for all the isolates. The lipase produced possessed activity and stability over a range of pH values and high thermal stability at ambient temperatures making them suitable candidates for industrial applications.

Keywords: Palm oil mill effluent, Lipolytic activity, Titrimetry, Enzyme stability