Short-chain ester synthesis by transesterification employing poly (MAc-co-DMA-cl-MBAm) hydrogel-bound lipase of Bacillus coagulans MTCC-6375

摘要

Lipases (E.C. 3.1.1.3) have been extensively used to achieve various esterification reactions in water-restricted or water-free media. In the present study a purified thermotolerant alkalophilic extracellular lipase of Bacillus coagulans MTCC-6375 has been efficiently immobilized onto a synthetic poly (MAc-co-DMA-cl-MBAm) hydrogel by surface absorption, and the bound lipase was used to perform short-chain fatty acid ester synthesis in n-alkane(s). The hydrogel bound lipase resulted in approximately 67 mM of isoamyl acetate at 55 degrees C in n-heptane under shaking in 15 h when vinyl acetate:isoamyl alcohol was used in a ratio of 100 mM:100 mM. Addition of a molecular sieve (3 angstrom x 1.5 mm) to the reaction system at a concentration of 25-500 mg per reaction volume had deleterious effect on the conversion of reactants to isoamyl acetate (64 mM). During the repetitive esterification under optimal conditions, the hydrogel bound lipase produced 31.3 mM of ester after fourth cycle of reuse. Use of methanol and 2-propanol (instead of isoamyl alcohol) resulted in 78.2 and 64.9 mM of methyl acetate and 2-propyl acetate, respectively, under the optimized conditions in n-heptane (C) 2008 Wiley Periodicals, Inc.