new extracellular thermo-solvent-stable lipase from Burkholderia ubonensis SL-4: Identification, characterization and application for biodiesel production

In the present study, a new lipase SL-4 from Burkholderia ubonensis SL-4, was purified by 80% ammonium sulphate precipitation, Q Sepharose FF anion exchange and Superdex 75 gel filtration chromatography finally leading to 68.5-fold purification and 13.34% recovery. It had a molecular mass of ca. 33 kDa and the whole gene (1095-bp) was cloned by using degenerate primers. Amino acid sequence analysis revealed that lipase SL-4 is a new member of subfamily 1.2 lipases. Lipase SL-4 exhibited optimum activity toward p-NP myristate (C14) at pH 8.5 and 65 degrees C with a K-m of 0.72 mM, a k(cat) of 391.63 s(-1) and a k(cat)/K-m of 543.93 s(-1) mM(-1). It had good thermostability at 50 degrees C and pH 8.5, and could be activated strongly by Ca2+ and Mn2+, but inhibited by some transition metal ions and EDTA, PMSF, DTT and beta-ME. Additionally, lipase SL-4 possessed non-ionic detergent stability and organic solvent stability. When preliminarily employed to catalyze soybean oil for biodiesel production, the liquid lipase SL-4 could attain a conversion ratio of 92.24% in a solvent-free system. These results demonstrate that the new thermo-solvent-stable lipase possesses an attractive potential for biotechnological applications as biocatalyst, especially for biodiesel production. (C) 2016 Elsevier B.V. All rights reserved.