Isolation and characterization of a thermophilic lipase from Bacillus thermoleovorans ID-1

A thermophilic microorganism, Bacillus thermoleovorans ID-1, isolated from hot springs in Indonesia, showed extracellular lipase activity and high gro wth 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 d egrees 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 vari ety of lipid substrates such as oils (olive oil, soybean oil and mineral oi l), triglycerides (triolein, tributyrin) and emulsifiers (Tween 20, 40). Th e excreted lipase of ID-1 was purified 223-fold to homogeneity by ammonium sulfate precipitation, DEAE-Sephacel ion-exchange chromatography and Sephac ryl S-200 gel filtration chromatography. As a result, the relative molecula r mass of the lipase was determined to be 34 kDa on sodium dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme showed optimal ac tivity at 70-75 degrees C and pH 7.5 and exhibited 50% of its original acti vity after 1 h incubation at 60 degrees C and 30 min at 70 degrees C and it s catalytic function was activated in the presence of Ca2+ or Zn2+. (C) 199 9 Federation of European Microbiological Societies. Published by Elsevier S cience B.V. All rights reserved.