Study of the Immobilization of β-Glucosidase onto Cross-linked Chitosan Microsphere

Objective:To optimize the immobilization of β-Glucosidase onto chitosan microsphere with glutaraldehyde.Method:Using activity of immobilized enzyme and activity recovery as response value,the effects of immobilization conditions and preparation conditions of cross-linked chitosan microsphere on immobilization were studied.Result:The optimal preparation conditions of chitosan microsphere were: 2.5% chitosan,2% acetic acid,7.5%NaOH,the ratio of NaOH and ethonal(v/v)=1∶1.The optimal immobilization conditions were as following: 0.1g wet chitosan microspheres was treated with 20mL 3% glutaraldehyde at 50℃ for 2h,then glucosidase was incubated with the microspheres for 24h at 25℃ with an enzyme loading of 7 388mU/g dry microspheres,giving the activity and activity recovery of the immobilized glucosidase 6188mU/g dry carrier and 95.4%,respectively.Conclusion: β-Glucosidase was immobilized by covalent bonding and the enzyme exhibited a considerable affinity to chitosan,giving high activity recovery while maintaining an optimum level of activity.