The Immobilization Of β-glucosidase And Its Application On The Synthesis Of Alkyl-glucoside

In this paper, the immobilization ofβ-glucosidase was studied using cross-linked chitosan microspheres, AB-8 resin and diatomite through covalent linkage and physical adsorption, respectively. Then the immobilized glucosidase was used to catalyze the reverse hydrolysis to synthesize butyl-glucoside. The main content and results are as follows:1. The cross-linked chitosan microsphere was used as the carrier to immobilizeβ-glucosidase through the covalent linkage. Using activity of immobilized enzyme and activity recovery as the response value, the effects of conditions in the preparation of cross-linked chitosan microspheres and immobilization process on the performence of immobilization were studied. The optimal preparation conditions of chitosan microsphere were: 2.5% of the final concentration of chitosan, 0.33% actate, the volume ratio of NaOH solution and ethanol was 1:1, 3.13%NaOH. The optimal process of immobilization was as follows: 0.1g wet chitosan microspheres mixed with 20mL of 3% glutaraldehyde and incubated at 50℃for 2h, then glucosidase was incubated with the cross-linked microspheres for 24h at 25℃with an enzyme loading of 7388mU/g dry microspheres, giving the activity and activity recovery 6188mU/g dry microspheres and 95.4%, respectively.2.β-glucosidase was immobilized onto the AB-8 macroporous resin through physical adsorption. The effects of enzyme loading, temperature, speed of oscillation and adsorption time on immobilization were studied. The optimal conditions of immobilization process: 0.8g AB-8 resins, 30℃, enzyme loading of 5000mU/g resin, 225rpm, 24h. The activity of the immobilized glucosidase and activity recovery reached 11049mU/g resin and 93.7%, respectively. However, glucosidase was not adsorbed onto diatomite under the reaction condition.3. Directβ-glycosidation for butanol in the presence of glucose using chitosan microphere immobilized glucosidase was carried out.The reaction was tracked by TLC and LC-MS. Four kinds of products were obtained. Probably chitosan was involved in the glycosylation. Additionally, apple seed meal was found a high enzyme activity material, but didn't yield any product under the reaction conditions. When the AB-8 resin immobilized enzyme was used in the synthesis, by analysing the IR and LC-MS of the product, we may speculate there is butyl-glucoside producing in the reaction.