Selective hydrolysis of coconut oil by microbial lipase
1989
Castillo, E.M.
Optimization of parameters for the extraction of lipase from Rhizopus arrhizus and Aspergillus niger was based on the amount of fatty acid released during incubation. The optimum incubation time for A. niger and R. arrhizus were found to be 7 and 8 days, respectively. It was found out that the optimum inoculum volume for A. niger is 15% using 2.02 x 10 to the eight power cell per ml of cell suspension and 2 flat bottle-slants per 10 of incubation medium for R. arrhizus. Optimization of the parameters on the fatty acid production of the crude extracellular enzyme was done. The parameters used were incubation time, temperature, and amount of enzyme solution. Results gathered showed that lipases from R. arrhizus and A. niger were most active at 40 deg C and 30 deg C, respectively. Optimum incubation time for A. niger is 47 hours and 40 hours for R. arrhizus. The optimum volume of enzyme solution is 10 ml for R. arrhizus and 9 ml for A. niger. Free fatty acids produced by the extracellular enzyme Rhizopus arrhizus at 40 deg C were esterified chromatographically. To identify the fatty acid produced, the retention times of the samples were compared with the retention times of the standards. The extracellular enzyme produced by R. arrhizus selectively hydrolyses the coconut oil, producing about 52-57% lauric acid, 18-18.6% myristic acid and 5-7% palmitic acid of the total fatty acids produced. A new fungus isolate Geotrichum candidum was screened for lipase production. The extraction was carried out at 30 deg C in shake flask cultures containing coconut oil as natural substrate. Optimum incubation time of the organism was evaluated using free fatty acid production occurred after the fungus was grown for 4 days. However, this result is not yet conclusive and further investigations are suggested to confirm observations.
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