Study On Methods, Characters And Applications Of Chitosan Immobilized β-D-Galactosidase

"Lactose malabsorption"is the bottleneck of the dairy industry development in our country. To make use of immobilizedβ-D-galactosidase to hydrolyze lactose in milk can settle"lactose malabsorption"effectively.This study adopted chitosan as carrier, and glutaraldehyde as crosslinked reagent to immobilizeβ-D-galactosidase. We used ways of covalent-crosslinked and absorption- crosslinked to find the conditions to immobilize lactase in different forms of chitosan in order to pick out an optimal condition for immobilization. Based on above researches, we had studied the characteristics of the immobilized lactase that had been prepared under the optimal conditions. Additional, we had compared five methods which mensurated ratio of hydrolyzed lactose in order to find a method that is simple,nicety and economy. The results were as follows:1. Compared among five methods including Fehling method, the colorimetric method of Anthrone, the Sacchairmetry, iodine number method and enzyme catalyzed method. The result showed that enzyme catalyzed method was a nicety, economy, simple and convenient way to mensurate content of lactose.2. Studied of the methods of three forms of chitosan including membrane,gelatin and bead to immobilizeβ-D-galactosidase as well as activity recycle rate. The results showed that the activity recycle rate of chitosan bead adsorption-crosslinked with glutaraldehyde immobilized lactase reached to 52.9%, chitosan gel covalent-crosslinked with glutaraldehyde reached immobilized lactase to 71.1%, chitosan membrane covalent-crosslinked with glutaraldehyde immobilized lactase reached to 77.8%.3. The immobilization conditions of enzyme were confirmed. The best efficiency of immobilization could be obtained under the condition that the concentration of glutaraldehyde was 2.5%, the pH of glutaraldehyde was 6.5, the adding amountβ-D-galactosidase was 0.4mg/mL, crosslink and immobilization time both were 12 hours.4. The characters of chitosan membrane covalent-crosslinked with glutaraldehyde immobilized lactase had changed. Compared with free lactase, the the optimum pH shifted from 6.8 to 6.5, the optimum temperature for immobilized lactase shifted from 40℃to 45℃.Under the condition of 60℃/1h, it was still left 50% avtivity while the free lactase lose acvtivety completely. Km for immobilized lactase had just a little difference from free lactase,...