Abstract: Magnetic immobilized enzymes are widely employed in magnetically stabilized fluidized bed reactor. The magnetic immoblized cellulases were prepared by immobilized cellulases on magnetic chitosan microspheres using the physical adsorp-tion method, and their magnetic responsiveness was investigated. The results demonstrated the optimum conditions of prepar-ing immobilized cellulase were: pH5.0, buffer solution concentration of 0.05mol/L, the amount of cellulase used of 150mg, immobilization time of 10h. And the activities of the magnetic immobilized cellulase and free cellulase exposed to the external magnetic field were measured. It was indicated that the activities of free cellulase increased with the increasing of magnetic field intensity when the intensity was less than 500mT and the exposure time was less than 60min, however, out of this range, a sharp decrease on the activities was detected. And the change of the activities of magnetic immobilized cellulases showed the same trend as that of free cellulases.

Key words: magnetic immobilized cellulase, enzyme activity, external magnetic field, magnetic responsiveness, magnetic field intensity, exposure time