Immobilization of Trehalose Synthase with Chitosan as the Carrier

In this research, trehalose synthase (TreS) was expressed using Escherichia coli BL21.Then, the purified enzyme was immobilized by chitosan according to adsorption method. After single-factor experiments, the optimal amount of the immobilized enzyme was 32.0 mg per gram of chitosan, the optimum time of binding was 2.5 hours. The optimum reaction temperature and pH of the immobilized enzyme were 40℃ and 6.0, respectively. The highest activity recovery of the immobilized enzyme was 40.17%. The rate of residual enzyme activity of the immobilized enzyme was 64.64% after consecutive 9 cycles, which had reusability a good. The thermal stability of the immobilized enzyme was not significantly different compared with the free enzyme, and the relative activity maintained 87% after preincubation of the immobilized enzyme at different temperatures (4~60℃) for 20 min. However, the pH stability of the immobilized enzyme was superior, and the relative activity still retained 60% after preincubation of the immobilized enzyme in various pH values (3.5~8.5) for 20 min. The results of reaction processes indicated that the maximum trehalose yield of this immobilized enzyme was 61.4% at the point of 2 hours.