Efficient Candida rugosa lipase immobilization on Maghnite clay and application for the production of (1R)-(-)-Menthyl acetate

This work focused on the identification of natural, economical, and efficient supports for immobilization of Candida rugosa lipase (CRL) to catalyze the resolution of (+/-)-menthol. To this purpose, CRL has been immobilized on natural montmorillonite from Algeria (Maghnite-H), ion-exchange resins (Amberjet(A (R))1200-H and Amberjet(A (R))4200-Cl), and diatomaceous earth (Celite(A (R))545). After a preliminary screening of supports, the immobilization of CRL led to a markedly improved enantioselectivity. Excellent enantioselectivity (E >= 134) was achieved by the four supported lipases (E = 68 for free enzyme). Compared to the three other supports tested, higher enantioselectivity was observed with Maghnite-H used as immobilization matrix. In this work, the effects of solvent, reaction time, and temperature, on the conversion as well as on enantioselectivity were investigated. The maximum of conversion (% C = 43%) with high enantiomeric excess of products (eep > 99) was obtained when the reaction is catalyzed by CRL immobilized on Maghnite-H at 30 A degrees C for 24 h, and using toluene as selected solvent. Immobilized CRL on Maghnite-H exhibited good thermostability over a wide temperature range (30-90 A degrees C) compared to the free one. These results suggest that CRL immobilized on Maghnite-H has good potential as biocatalyst for the production of (1R)-(-)-menthyl acetate.