Cloning, expression, and biochemical characterization of a thermostable lipase from Geobacillus stearothermophilus JC

Abstract

A thermophilic lipase gene of Geobacillus stearothermophilus JC was cloned and expressed in a pET 28-a (+) expression vector. The biochemical properties of the recombinant enzyme and its enantioselective hydrolysis of (RS)-1-phenylethyl acetate were studied. Removal of the signal peptide greatly increased the enzyme’s expression level by 4.3 times. The purified JC lipase had an optimum temperature of 55°C and optimum pH of 9. Furthermore, comparisons with other enzymes suggest that a few amino acid alterations may significantly change the thermostability of this enzyme. The hydrolysis of (RS)-1-phenylethyl acetate with the crude recombinant JC lipase at 25°C produce (R)-1-phenylethanol in 97.7% e.e. and 46.1% yield after 24 h, corresponding to an E value of 237.