Abstract:

β-Galactosidase was immobilized on chitosan microspheres with glutaraldehyde by cross-linking reaction, the immobilezation conditions and characterization of the immobilized enzyme were studide. The optimal conditions for immobilization were as follow:in pH6.5 P-E-M solution for 10 h, chitosan microsphere was treated with 0.5% glutaraldehde at 25℃ for 12h,the solution ofβ-galactosidase was immobilized on the carrier at 4 ℃ for 12 h, enzyme activity recovery was 67%. Optimal temperature and pH for the immobilized enzyme were about 40 ℃ and 7.0 respectively,apparent michealis constant of immobilized β-galactosidase Km=0.613mmol/L.The stability of immobilizedβ-galactosidase was high after storage. It exhibited excellent operational stability．With 5% lactose as the substrate，the lactose hydrolysis was maintained at 90% after 6 cycles；the lactose hydrolysis was kept at 75% when the immobilized lactase was applied in the column chromatography reactor after 20 days.

Key words: chitcsan, microspheres, immobilization, β-galactosidase, operational stability