Characterization of thermostable lipase from thermophilic Geobacillus sp. TW1

A novel lipase-producing thermophilic strain TW1, assigned to Geobacillus sp. TW1 based on 16S rRNA sequence, was isolated from a hot spring in China. Based on this strain, a lipase gene encoding 417 amino acids was cloned. Subsequently, the lipase gene was expressed in Escherichia coli and purified as a fusion protein with glutathione S-transferase. The results showed that the recombinant lipase had an activity optimum at 40 °C and pH at 7.0-8.0. It was active up to 90 °C at pH 7.5, and stable over a wide pH ranging from 6.0 to 9.0. The recombinant lipase was stable in 1 mM enzyme inhibitors (EDTA, 2-ME, SDS, PMSF or DTT), as well as in 0.1% detergents (Tween 20, Chaps or Triton X-100). Its catalytic function was enhanced in the presence of Ca2+, Mg2+, Zn2+, Fe2+ or Fe3+, but inhibited by Cu2+, Mn2+, and Li+. By comparison with the crude lipase, the recombinant lipase had similar properties and was characteristic of thermostable enzymes. Our study presented a rapid overexpression and purification of the lipase gene from thermophile, aimed at improving the enzyme yield for industrial applications.