Study on Nano-SiO2 modified chitosan carrier and immobilization of chitosanase

Chitosanase was immobilized on hybrid carrier by cross-linking reaction with glutaraldehyde. The carrier was formed by the sol-gel of TEOS which doped with chitosan. Characterization of carrier was verified with Scanning Electron Microscopy (SEM) , Infrared spectrum and X-ray diffraction while characteristics of the immobilized chitosanase and free chitosanase were compared. Results showed that the optimal conditions for immobilization were as follows:5% solution of glutaraldehyde and 2m (U=2.5) chitosanase immobilized on the carrier possessed the highest chitosanolytic activity. Optimal pH for the immobilized enzyme was 7.0 so that the enzyme activity curve of the immobilized chitosanase moved to the alkaline relative to free chitosanase. After the chitosanase immobilized, optimal temperature was increased by 5℃. There was wider temperature in the scope of enzyme activity. Through the Lineweaver-Burk mapping, the K' m which was 10. 64g/L for immobilized enzyme was rised significantly than the Km'which was 1.29g/L for free enzyme. The immobilized enzyme showed better operation and storage stability than the free enzyme. Reused 10times, the loss of enzyme activity was less than 30%. At 4℃, the stability of immobilized enzyme was good, and the half-life was approximately 28d.