Biosynthesis And Fractionation Of Xylanase

Xylo-oligosaccharide, the product of biodegradation of hemicellulose, is the high additional value substance. Nowadays, there have raised a research upsurge of the functional food in the world. However, the biodegradation of xylan to prepare xylo-oligosaccharide is still the main method in present days.This dissertation studied the biosynthesis of xylanase by different degree of polymerization substrate, the effect which xylanase characteristics and enzymatic hydrolysis condition have made on the preparation of xylo-oligosaccharide, fractionate xylanase in order to improve the gain ratio and the purity of the xylo-oligosaccharide, and also offer the theoretic basis for the industrial use. The main results are as follows:The substrate of low degree of polymerization, such as enzymatic hydrolysis residue, could induce high activity of the xylanase. In this case, the xylanase activity (75.65IU/mL) raised 33% as per the crude xylan of relative high degree of polymerization. When kept the low concentration of the substrate of enzymatic hydrolysis residue (7g/L), it could conduce to enhance the gain ratio of the xylanase . The purity and gain ratio of the xylo-oligosaccharide were also improved. The xylo-oligosaccharide accounted for 38.67 % of the total sugar in the hydrolysate and the enzymatic hydrolysis efficiency was 42.63 %. For the substrate of enzymatic hydrolysis residue, which was the massive waste of enzymatic hydrolysis , could induce high activity of the xylanase. There are 75.41 % pentosan in the enzymatic hydrolysis residue, so using the enzymatic hydrolysis residue as the substrate could decrease the cost of the preparation of the xylanase. And this could also increase the effective use of the xylanase production material.It had better to add 5 % enzyme and enzymatic hydrolysis 4h in order to increase the effective use of the xylan material and enhance the gain ratio of the xylo-oligosaccharide .In this case, the gain ratio of the xylo-oligosaccharide was the greatest at 13.69 %. The xylo-oligosaccharide accounted for 44.53 % of the total sugar in the hydrolysate and the ratio of the xylo-oligosaccharide and xylose was 0.8.When added (NH4)2SO2 to the xylanase , it could eliminate some -xylosidase. After the treatment, the gain ration of the xylo-oligosaccharide , the ratio of the xylo-oligosaccharide and the xylose or the total sugar were all greater than that untreated xylanase. Moreover, the gain ratio of the xylose decreased markedly. When added 5 % enzyme and enzymatic hydrolysis 4h, the gain ratio of the xylose was only 1.03 g/L, xylo-oligosaccharide accounted for 89.53 % of the total sugar in the hydrolysate. And the gain ratio of the xylo-oligosaccharide was 25.17%.The effect of the enzymatic hydrolysis became better when the xylanase was treated by ultrafiltration. This treatment could reduce the activity of the P -xylosidase distinctly and thereby unproved the purity and gain ratio of the xylo-oligosaccharide. The content of the xylose in the xylo-oligosaccharide was also decreased. When added 10 % enzyme and enzymatic hydrolysis 8h, the gain ratio of the xylo-oligosaccharide and xylose were 34 % and 1.91 % respectively. However, added 5 % enzyme and enzymatic hydrolysis 8h, xylo-oligosaccharide accountedfor 96.25 % of the total sugar .The ratio of the xylo-oligosaccharide and xylose was 25.63 %.After a series of fractionation, the configuration of the component B, C and D was reasonable. The purity and gain ratio of the xylo-oligosaccharide were all great comparatively, especially for the component C. When enzymatic hydrolysis 4h, the gain ratio of the xylo-oligosaccharide was the greatest at 28.48 %. The ratio of the xylo-oligosaccharide and xylose was 12.17 % , and the xylo-oligosaccharide accounted for 92.41 % of the total sugar in the hydrolysate. It was concluded that the component C was better for the production of xylo-oligosaccharide.