Immobilization of lipase on magnetic porous microspheres

The immobilization of Arthrobacter sp. lipase on magnetic porous microspheres was investigated. The magnetic porous microspheres was characterized with FTIR，XRD，SEM，TEM，BET，TGA and VSM，and the effect of immobilization time，pH，and lipase amount on the catalytic performance of the immobilized lipase in an organic system was studied. The results showed that the core of microsphere was Fe₃O₄，the surface was porous，the surface area of microsphere was 12.16 m²/g，average pore diameter was 171.7 nm，its magnetic content was 38% and it was super-paramagnetic. The optimal immobilization conditions were determined to be pH 8.0 with the lipase/carrier ratio of 1 to 1（m/m）and immobilization time of 6 h. The activity recovery was as high as 2.4 fold of the free lipase in the resolution of 4-hydroxy-3-methyl-2-（2-propenyl）-2-cyclopenten-1-one. Furthermore，the operational stability of the immobilized enzyme was greatly enhanced compared to the free enzyme. The residual activity was kept at 74.5% after 30 batch reactions，while that of the free enzyme was just 37.1% after 7 batch reactions.