Abstract:

The chitosanase in the fermentation broth of B.thuringiensis ZJOU-010 was immobilized by adsorption onto DEAE- 22 cellulose and cross-linking with glutaraldehyde. The immobilization conditions of this enzyme were investigated. Apart from this, its enzymatic properties after the immobilization were characterized. The optimal enzyme immobilization process determined was that the immobilization was allowed to proceed for 10 h under the conditions of 3.0% glutaraldehyde concentration and 20 mg enzyme loading. The optimal pH and temperature of the immobilized enzyme obtained under these conditions were 4.83 and 50 ℃, respectively. It had better thermostability than its free counterpart, displaying half-lives of 36.3 h at 40 ℃ and 6.2 h at 50 ℃ and a kinetic parameter Km of 9.19 g/L. After being repeatedly used for 10 times, the residual activity of the immobilized enzyme as percentage of original activity was 88.32%.

Key words: chitosan, chitosanase, immobilization, cross-linking, DEAE-22 cellulose