Expression and characterization of a novel cold-adapted lipase from psychrotolerant bacteria Psychrobacter sp. S1B

ABSTRACT

@#Aim: This study aimed to isolate, express and characterize the lipase derived Psychrobacter sp. S1B in Escherichia coli expression system. Methodology and results: Exploration towards S1B lipase characteristic was conducted where shotgun cloning method was applied to obtain lipase encoded gene and E. coli expression system through pET28a was used to overexpress S1B lipase. Lipase activity was measured by using p-nitrophenol method. The S1B lipase gene is 1005 bp in length with molecular weight of 46 kDa, optimum pH was 10.0, showed hydrolytic activity preference toward p-nitrophenyl caprylate (C8) and p-nitrophenyl hexanoate (C6) substrates (C6 < C8). The best temperature for S1B lipase activity was at 30 °C while exhibited high activity at lower temperature (10-25 °C) with above 90% of maximum activity, therefore it is classified as cold adaptive lipase. In addition, S1B lipase showed stability against various metal ions, including Cu2+ and Zn2+ which commonly act as inhibitors of lipases derived from Psychrobacter species. Moreover, S1B lipase exhibited great tolerance against up to 50% (v/v) hexane and some non-ionic detergents such as 1% (v/v) DMSO and 1% (v/v) Triton X-100. Conclusion, significance and impact of study The study proposes a novel cold-adapted lipase which has potential as a biocatalyst for synthesis caprylic acid ester