The Immobilization Of β-galactosidase On Chitosan

β-galactosidase was immobilized on chitosan microsphere with 2,4,6-trichloro-1,3,5-tri-azine as crosslinker, and compared with that using glutaraldehyde as crosslinker. After getting the best conditions of the carrier, various factors were discussed to determine the finest immobilization conditions. The enzyme activity recovery determined was 47% at the optimal condition. The results obtained showed that the immobilization was simple and efficient. So, 2,4,6-trichloro-1,3,5-triazine was a kind of good crosslinker to immobilize enzyme.Chitosan with different molecular weight (50×104, 100×104,200×104) was used as material to immobilizeβ-galactosidase, the results obtained showed that 50×104 chitosan was the most suitable to immobilzeβ-galactosidase because its appropriate viscosity, easy-ball, the highest enzyme activity and the recovery. In additon, a new method to make chitosan macrospheres was offered in this paper, and it was much simpler and faster than the traditonal method. Finally, it was also found that the dried chitosan macrospheres could keep nearly the same structure as the wet one after being treated with 30% glycerol solution, which was very useful to the enzyme immobilzation with chitosan macrospheres as carrier in industry.Porous chitosan macrospheres were prepared by using silica particles as porogen at the first time. Scanning electron microscopy (SEM) micrographs showed that the support with silica as porogen (supportⅠ) had a much more porous surface structure than the support without porogen (supportⅡ), then both supports were applied to immobilizeβ-galactosidase from Aspergillus oryzae, much higher specific activity and activity yield were observed for the supportⅠ. Finally, Properties of both immobilized enzyme were determined and compared with the free enzyme, satisfactory results were obtained in thermstability, pH and operational stability, Michaelis constants Km and the maximum velocity (Vm). Results above showed that the enzyme prepared by using silica particles as porogen is very good, and it will has more applization.