Jayanath_2018_Int.J.Biol.Macromol_119_393

A novel esterase, designated as EstSP was identified by function based screening from a soil metagenomic fosmid library of solar saltern of Goa. EstSP gene of 1065bp encoding a putative esterase of 354 amino acids showing 55% identity to esterase from gamma proteobacterium HIMB55 was identified. The enzyme EstSP belongs to family IV hormone sensitive lipase with novel sequence characteristics and a unique motif GDSGG. EstSP expressed as a His-tag fusion protein of mass 58kDa was visualized on SDS PAGE and confirmed by Western blot analysis. The enzyme is an alkaline esterase that exhibited highest catalytic activity towards p-nitrophenyl acetate with optimum temperature 40 degrees C and pH8.0. The catalytic efficiency and specific activity of EstSP for p-nitrophenyl acetate was 7407.4min(-1)mM(-1) and 915.23Umg(-1) respectively. EstSP showed remarkable stability in the presence of polar and non-polar solvents, retaining >80% of its activity after 72h. Furthermore, the enzyme is halotolerant with optimum activity at 1M NaCl and maintained 60% residual activity after 24h exposure to 5M NaCl. This novel enzyme with remarkable properties could be a promising candidate for industrial bioprocesses in non-aqueous media as well as pharmaceutical, food and biotechnological applications.