초록
An extracellular halo-thermo-tolerant, solvent stable lipase was purified and characterized for its multifunctional activity of catalyzing transesterification, esterification and hydrolysis reactions for biodiesel production, flavor agent synthesis and for the selective enrichment of monounsaturated fatty acid (MUFA) respectively. The purified enzyme showed optimum activity at pH 7 and temperature 30<SUP>o</SUP>C. The enzyme was found to be stable at broad ranges of pH (5.0-9.0), temperature (10-60<SUP>o</SUP>C) and salinity (up to 30%). Interestingly, the enzyme showed stability in different polar solvents of log P<2 at a concentration of 75% (v/v) for 7 days. The solvent stability of lipase was utilized for biodiesel production by transesterification of different oils and the results revealed the conversion (%) of 99% for palm oil, 85% for cotton seed oil, and 75% for waste vegetable oil. The lipase catalyzed hydrolysis of Chlorella oil showed selective enrichment of oleic acid content with a substantial 3-fold increase in concentration. Further, the esterification reaction catalyzed by lipase showed a conversion rate of 23% for synthesis of ethyl lactate and 31% for butyl acetate. The lipase production was also optimized using different low cost substrates. The lipase enzyme was immobilized over magnetic iron-oxide nano-particles and the recyclability of the enzyme was shown practically unchanged for seven consecutive cycles. The shown multifunctional catalytic activities by Bacillus lipase and its production on low cost substrates coupled with recyclability will aid in reducing the capital cost for developing greener industrial processes in biorenewables and synthetic chemistry.