New Insight into Old Bacillus Lipase: Solvent Stable Mesophilic Lipase Demonstrating Enzyme Activity towards Cold

Abstract

<b><i>Background:</i></b><i>Bacillus</i> lipases are grouped in subfamily 1.4, which are the smallest known lipases having a molecular mass of 19.6 kDa. Lipases active in a wide range of temperatures, specifically at low temperatures, have an advantage under low water conditions for industrial application. <b><i>Methods:</i></b> The lipase gene was cloned and expressed in <i>Escherichia coli</i>. The protein was purified and biochemically characterized in detail. <b><i>Results:</i></b> A lipase gene was cloned from a mesophilic <i>Bacillus</i> isolate. Sequence analysis revealed an open reading frame of 633 bp in length. The predicted molecular mass of protein was 22.6 kDa. The purified enzyme displayed optimal activity at 35°C and pH 8.0. Interestingly, this mesophilic enzyme was also cold active showing retention of 75 and 55% relative enzyme activity at 20 and 10°C, respectively. The purified lipase was stable in various organic solvents (50% v/v) and ionic liquids (5% v/v). The enzyme displayed maximum activity with paranitrophenyl laurate (C₁₂). k_cat/K_m values for the purified lipase were calculated to be 5.8 ± 0.6 × 10^-6. <b><i>Conclusions:</i></b> The lipase showed tolerance to various solvents as well as activity at low temperature. Therefore, this lipase might be of great potential to be employed in various industrial applications.