Study On Production And Applications Of Xylanase From Thermoascus Aurantiacus

Xylanase is used in hydrolysis of hemicellulose, paper industry, food, and animal feed industries. A lot of agro-industrial, agricultural and forest by-products, which are rich in cellulose and hemicelluloses, are engendered every year in our country. These by-products are not effectively reused till now. Currently, more and more efforts are directed towards the re-use of such by-products, considering economic values and environment. Fractionation of these by-products into their main components could be of interest to obtain separate streams useable for different product applications. Since the main component of the hemicellulose in the by-products mentioned is xylan, fractionation of these by-products may result in a variety of differently substituted xylooligosaccharides that are reported to enhance growth of bifidobacteria and frequently defined as prebiotics. Xylooligosaccharide production from the hemicellulose of these by-products by xylanase hydrolysis has important social value and apparent economic value.Xylanase production by Thermoascus aurantiacus. the enzymatic characteristic of Thermoascus aurantiacus xylanase, enzymatic hydrolysis of cellulosic materials and xylooligosaccharides production from the hemicellulosic hydrolysate were studied in the thesis. Under the optimal culture conditions, the activity of xylanase production in submerged fermentation and in solid state culture reached 912 U/mL and 16.58 X 104 U/g, respectively.The studies on the enzymatic characteristic showed that T. aurantiacus xylanase was a multienzyme and the major component of it was xylanase. The optimal temperature and pH value for the xylanase reaction were 75 "C and 4.8, respectively. The enzyme was stable in the pH 3.8-5.8 and was thermostable with more than 85% relative activity at 75 癈 for 60 min. The xylanase preparation was thermostable and had a good application potential in biobleaching.It was found that the xylanase pretreatment method is better than the dilute acid method because the properties of enzymatic hydrolysate were more suitable for fermentation and utilization than those of dilute acid hydrolysate. That xylanase first and then cellulase was the optimal hydrolysis process The optimum dosage of xylanase and cellulase were 7680 U and 12 FPIU per gram substrate, respectively.ABSTRACTThe hemicellulose extraction yield from corn bran was 93.9% under optimal extracting conditions. Using ethanol to make hemicellulose depositing was studied for removing the sodium chloride from the hemicellulose substrate. Optimal hydrolysis parameters of hemicellulose to produce functional xylooligosaccharides by xylanase were: enzyme dosage 720 U/g hemicellulose and substrate concentration 3.0-4.0%. The reaction time can be controlled acording to the requirement average DP of the product. The xylooligosaccharides from corn bran by xylanase hydrolysis had a wonderful market potential and was considerable profitable.