Influencing Factors on Lipase Production by Thermophilic Bacteria, Geobacillus stearothermophilus PTL38

Abstract

Thermophilic Geobacillus stearothermophilus PTL38 isolated from grease chamber of restaurant in Amphoe Moungubonratchathani, Ubon Ratchathani Province. This bacterium produces lipase with hydrolytic activities when cultures in enrichment medium B comprised with basal salt solution, 0.5 % w/v yeast extract, 1 % v/v olive oil. Factors affecting the lipase production were examined. It was observed that modified enrichment medium B with 7.0 initial pH of the medium, 36 hrs inoculums age, 5.0 % (v/v) inoculums volume, 36 hrs and 55 °C incubation with 180 rpm shaking. Under this optimized condition, the bacterium gave 36.50 U/ml of maximum lipase production. G. stearothermophilus PTL38 utilized several commercial vegetable oils as carbon source. Palm oil (2.5 %, new) and corn oil (1.0 %, reuse twice) were the best among all carbon sources tested, yielding 40.60 U/ml and 42.40 U/ml lipase, respectively.