Medium-based optimization of an organic solvent-tolerant extracellular lipase from the isolated halophilic Alkalibacillus salilacus

A haloalkaliphilic solvent-tolerant lipase was produced from Alkalibacillus salilacus within 48 h of growth in liquid medium. An overall 4.9-fold enhanced production was achieved over unoptimized media after medium optimization by statistical approaches. Plackett-Burman screening suggested lipase production maximally influenced by olive oil, KH2PO4, NaCl, and glucose; and response surface methodology predicted the appropriate levels of each parameter. Produced lipase was highly active and stable over broad ranges of temperature (15-65 °C), pH (4.0-11.0), and NaCl concentration (0-30 %) showing excellent thermostable, pH-stable, and halophilic properties. The enzyme was optimally active at pH 8.0 and 40 °C. Majority of cations, except some like Co(2+) and Al(3+) were positive signals for lipase activity. In addition, the presence of chemical agents and organic solvents with different log P ow was well tolerated by the enzyme. Finally, efficacy of lipase-mediated esterification of various alcohols with oleic acid in organic solvents was studied.