Purification and characterization of a mesophilic lipase from Bacillus subtilis FH5 stable at high temperature and pH.

Lipases are a class of enzymes which catalyze the hydrolysis of long-chain triglycerides. Microbial lipases are currently receiving much attention with the rapid development of enzyme technology. Bacillus subtilis FH5, isolated from tannery wastes, produced a thermostable alkalophilic lipase and was purified to homogeneity as judged by SDS-PAGE. The purification steps included acetone fractionation and sequential column chromatography on DEAE-cellulose, Sephadex G-75 and adsorption chromatography on Hydroxylapatite. The results of chromatographies showed that two types of lipases were present having molecular weights approximately 62 kDa and 24 kDa, respectively. The purified enzyme was found to be 100% stable at pH 10 and about 80% residual activity was present at 60 degrees C. The enzyme was found to be stable in the presence of Mg2+, Mn2+ and Ca2+ ions. Km value was calculated as 5.05 mM and Vmax as 0.416 micromol/ml/min. Bacillus subtilis FH5 was isolated from tannery waste, therefore, enzyme is environmentally compatible for application in leather degreasing process.

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