Characterization of lipase produced by Bacillus sp. FH5 in immobilized and free state

摘要

Microbial lipases have a great potential due to the rapid development of enzyme technology and their industrial applications. Lipase was produced by Bacillus sp. FH5 and partially purified by acetone precipitation. It was immobilized on silica gel. Lipolytic activity of the enzyme in free as well as immobilized state was compared. Lipolytic activity was determined by using p-nitrophenyl laurate as substrate and measuring the absorbance at 420 nm. Lipolytic activity was higher in immobilized crude enzyme as compared to that of free-state. A sharp decrease in lipolytic activity was observed in case of free and immobilized crude enzyme at 50 and 55°C, respectively. The lipase activity of both free and immobilized crude extracts was inhibited when incubated with serine reagent PMSF and SDS. Both the free and immobilized crude lipase forms were found to have a stimulatory effect in the presence of Mg+2, Fe+3, and Ca+2, whereas K+, Cu+, Na+2, Zn+2, and Ni(NO₃)₂ showed an inhibitory effect on the activity of free as well as immobilized crude lipase. Maximum lipolytic activity was found in the presence of 20% ethanol both in the case of free and immobilized crude lipase.