Optimization of lipase production using response surface methodology by a newly isolated, Bacillus sp. UMK-HS6.

Samples were collected from different sources in palm oil mill factory located in Kulim, Kedah. Screening of lipase producing bacteria was done on Tributyrin agar plate and formation of zone of hydrolysis was observed. Total of 18 isolates were characterized and identified based on morphological properties, colony characteristics and biochemical properties. Isolate UMK-HS6 was selected for its maximum yield of lipase (627 U/ml) and identified as Bacillus cereus via 16S rRNA analysis, a Gram positive bacilli. The optimum media composition derived from Response Surface Methodology (RSM) was consisted of (per liter): peptone, 54.99g; NaCl, 2.92; olive oil, 5.48ml with the lipase activity was 687 U/ml. Optimum culture conditions was observed when 7% of Bacillus cereus UMK-HS6 inoculated in the media containing above composition at pH 6.9 with agitation speed of 234 rpm for 24 hours. The lipase activity had increased more than 30% (1020 U/ml) upon the exposure in the optimum media and culture condition. Crude extracellular lipase enzyme was characterized for its activity and stability profile towards pH and temperature and both pH 6.0 and temperature, 30°C were observed to be the best condition for enzyme in 25 hours incubation.