edison seamount로부터 분리한 신규 esterase

Abstract

Organic solvent tolerant enzymes are being exploited to use as a biocatalyst in novel biotechnological applications. A Gram-negative, motile, rod-shaped, psychrophilic and lipolytic bacterial strain, SL13T, was previously isolated from deep-sea sediments (1450 m depth) of Edison Seamount in the western Pacific Ocean and identified as Photobacterium frigidiphilum sp. nov. In this study, a novel organic solvent tolerant esterase gene (estSL13) was cloned by activity-based screening a genomic library of P. frigidiphilum SL13T. The sequence analysis revealed that estSL13 consisted of 921 bp, corresponding to 306 amino acids with a molecular mass of 34,568 Da, and EstSL13 was assigned as an esterase belonging to family V of bacterial esterases/lipases. The recombinant esterase (rEstSL13) was overexpressed in a soluble form in E. coli and purified to homogeneity. rEstSL13 was active in a broad temperature range from 30 to 50oC, with an optimum temperature at 35oC and had an optimum pH at pH 8.0. rEstSL13 preferentially hydrolyzed p-nitrophenyl esters of fatty acids with short chain lengths of £ 10 carbon atoms among the p-nitrophenyl esters (C2 to C18) tested and was classified as an esterase due to their absence of activity toward tricaprylin (C8). rEstSL13 is very stable in the presence of organic solvents, and these features make it a very attractive enzyme for the biotechnological applications as a biocatalyst.