Melia azedarach leaf powder stabilizing Pseudomonas fluorescens lipase to catalyze synthesis of geranyl acetate

Abstract

To improve the stability of lipases in organic phases and promote the enzymatic synthesis, the inexpensive Melia azedarach leaf powder was taken as carrier for lipase immobilization, which was considered as solid “water” that could stabilize enzyme proteins. On the leaf powder, Pseudomonas fluorescens lipase was immobilized by physic adsorption in a column glass bottle and used for synthesis geranyl acetate via transesterification of geraniol and vinyl acetate. It is found that the immobilized lipase prepared in a mass ratio of 10 : 25 (enzyme: leaf powder, mg: mg) not only has a fine catalytic activation but also has an excellent nonaqueous stability in solvent-free nonaqueous reaction system composed of 1 mL geraniol and 2 mL vinyl acetate. Namely, the best loading of this immobilized lipase was 11.7 mg mL −1 in the reaction system in which, at 37°C and 160 rpm, the reaction conversion reached 90.1% after 10 h and achieved at 99.3% after 16 h. And after undergoing six times of 10-h reuses, the immobilized lipase had no decrease in the catalytic ability of converting geraniol except a little fluctuation 0.09% h −1 in conversion during reuse. Differently, the native lipase showed an activity attenuation 0.61% h −1 in the organic system in the reuse. Obviously, this immobilized lipase has been significantly improved in the nonaqueous stability, meant great potential in practical application. • Melia azedarach leaf powder is a useful carrier for lipase immobilization. • Immobilized Pseudomonas fluorescens lipase is desired to prepare citronellyl acetate. • Reuses show that the immobilized lipase has little decrease in nonaqueous activity. • The bottle with immobilized lipase is a simple bioreactor with great potential.