关键词: 可逆溶解性聚合物, Eudragit L-100, 固定化, 球毛壳霉, 木聚糖酶, 低聚木糖

Abstract: Eudragit L-100, a reversibly soluble-insoluble polymer, was used for immobilization of xylanase of Chaetomium globosum for production of xylooligosaccharide. The immobilization was performed by a simple adsorption process. The maximum activity 10.6 IU/mg is obtained with 88.47% activity recovery at 1.0% polymer concentration. The optimum pH value increases one unit and the optimum temperature remains unchanged. The immobilized enzyme obviously enhances the thermal stability, and retains 65% of its initial activity after being hydrolyzed repeatedly xylan for six times. Moreover, the time course of hydrolysis of xylan by free enzyme as well as immobilized enzyme was also studied. Due to immobilization, the enzyme produces more reducing sugar than the free enzyme after being hydrolyzed for 24 hours. HPLC analysis indicated that xylobiose and xylotriose are both the immobilized end products with higher content of xylobiose than the free enzyme. whereas the xylobiose has become the major component instead of xylotriose after being immobilized. The enhanced characteristics of xylanase upon being immobilized may be helpful for the application of preparing xylooligosaccharide.

Key words: reversibly soluble-insoluble polymer, Eudragit L-100, immobilization, Chaetomium globosum, xylanase, xylooligosaccharide