Lipase of Bacillus stratosphericus L1: Cloning, expression and characterization

Present work was undertaken to discover new lipolytic enzymes as well as novel bacterial strains for applications in biotechnology. One of the isolated strains identified as Bacillus stratosphericus L1 produced extracellular lipase (LipBST) which was cloned and expressed in Escherichia coli. Purified mature enzyme had a molecular mass of 19kDa. Recombinant protein showed an activity of 6244.5U/mg at pH 9, 35°C. It was stable in the range of 35-55°C and retained more than 60% activity after incubation for 4h. LipBST was activated by organic solvents such as acetone and n-hexane. Lipase was inactivated by all investigated metal ions, inhibitors and detergents. LipBST was determined to be short-chain specific, but also hydrolyzed medium-, long-chain p-nitrophenyl and natural fatty substrates. The values of V_max and K_M for p-nitrophenyl butyrate, p-nitrophenyl caprylate, p-nitrophenyl decanoate were 1.1, 2.5, 0.1mMmin^-1 and 5×10^-2, 3.4×10^-2, 194×10^-2mM, respectively. Biochemical characteristics of LipBST suggest a great potential for various biotechnological applications including detergent formulation, bioremediation and organic synthesis processes.