Isolation and Optimization of Lipase Producing Bacteria from Oil-Contaminated Soils

Abstract

This research aimed to isolate lipase-producing bacteria from soil samples contaminated with vegetable oil or petrol, and then optimize the conditions for lipase production. The bacteria that could be grown on tributyrin agar supplemented with 1% palm oil and produced a wide clear zone were selected. These selected bacterial isolates were tested for lipase activity, among them, the isolate PKRU-9 had the highest lipase activity. Then, the optimum conditions for lipase production of the PKRU-9 were optimized. The maximum lipase production was obtained when PKRU-9 was cultured in a basal medium containing 0.5% yeast extract as a nitrogen source and 0.5% soybean oil as a carbon source at 200 rpm. After cultivation for 54h, the maximum lipase production was reached. Treatment of wastewater contaminated with lipid of PKRU-9 was studied by culturing the bacterium in synthetic wastewater medium containing 1% palm oil, and in wastewater contaminated with fat. PKRU-9 was able to decrease the value of BOD5 by 74% and 90%, respectively comparing to the starting BOD5. The highest percent reduction of BOD5 was found on day 3 of cultivation. These results suggested that the PKRU-9 has the potential to be used for treating municipal wastewater contaminated with fat.