Study On Xylooligosaccharides Production From Xylan With Xylanase Synthesized By Aspergillus Niger M1

The mycelial fungus Aspeigillus niger Ml was sieved which produced the highest level of xylanase and lowest of P - xylosidase. Its optimal culture conditions were as follows: corncob meal: wheat bran = 7:3,3% of ammonium sulfate in dry medium weight, dry medium:water = 1:2.0,temperature 301 and cultivation for 74 hours. The dry culture was extracted with distilled water at 30· for 1 hour. The culture supernatant was used as crude enzyme preparation. It didn' t contain any amylase. The xylanase and (3 - xylosidase activities of dry culture reached 3511.15 μmol · min -1·g -1 and 10.12μmol·min -1·g-1 respectively.The xylanase and β- xylosidase showed optimal activity at pH 4. 8, 4.0 and 50℃,60℃, respectively. The xylanase and (3 - xylosidase were stable in the pH range 5.0- 10.6 and 3.0-7.0, respectively. After the crude enzyme preparation was incubated at 50t for 24 hours, the residual relative activities of xylanase and f) - xylosidase were 12% and 72% respectively. The conditions of enzymatic hydrolysis of hemicellulose for production of more xylooligosaccharides were as follows:The optimal substrate was xylan from wheat bran. Its concentration was 2% and the xylanase content was lOOu/mL. All these compconents were incubated in pH4.8 buffer at 40t for 12 hours.The final enzymic hydrolysate was filtered, concentrated and separated by chromatography of charcoal column. The purified xylooligosaccharides were obtained. It was comprised of xylobiose, xylotrios, xylotetraose and xylopentaose. Its yield reached 25.5%...