A thermophilic microorganism, Bacillus thermoleovorans ID-1, isolated from hot springs in Indonesia, showed extracellular lipase activity and high growth rates on lipid substrates at elevated temperatures. On olive oil (1.5%, w/v) as the sole carbon source, the isolate ID-1 grew very rapidly at 65°C with its specific growth rate (2.50 h-1) and its lipase activity reached the maximum value of 520 U l-1 during the late exponential phase and then decreased. In addition to this, isolate ID-1 could grow on a variety of lipid substrates such as oils (olive oil, soybean oil and mineral oil), triglycerides (triolein, tributyrin) and emulsifiers (Tween 20, 40). The excreted lipase of ID-1 was purified 223-fold to homogeneity by ammonium sulfate precipitation, DEAE-Sephacel ion-exchange chromatography and Sephacryl S-200 gel filtration chromatography. As a result, the relative molecular mass of the lipase was determined to be 34 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme showed optimal activity at 70-75°C and pH 7.5 and exhibited 50% of its original activity after 1 h incubation at 60°C and 30 min at 70°C and its catalytic function was activated in the presence of Ca2+ or Zn2+. Copyright (C) 1999 Federation of European Microbiological Societies.
All Science Journal Classification (ASJC) codes
- Molecular Biology