Study On Preparation Of Xyooligosacchrides From Corncobs Xylan By Thermomyces Lanuginosus Xylanase DSM10635

Xylooligosaccharides are oligosaccharides composed of xylose unitslinks by β-1,4-xylosidete bonds. They have excellent physical and chemicalproperties and physiological activities, and the market prospect of thexylooligosaccharides is very good. Therefore they are widely studied allover the world.This dissertation studied the optimal conditions of extracting xylanfrom the corn cob at first. In order to get the crude xylan, the bestpretreatment and the different alkali concentration of the corn cob are usingthe pretreatment of the distilled water and high temperature steaming, then15%sodium hydroxide solution of high-temperature alkaline hydrolysis.The xylan yield is33.6%.The crude xylan was refined by decolorizing with35%hydrogen peroxide and removing the protein of10%trichloroaceticacid and the collected rate is24.4%. Comparing with the Michael’s constantof the same xylanase produced by Thermomyces lanuginosus DSM10635，which separately used different kinds of xylan and xylan extracted fromcorn cob as substrates， Km7.5303mg/mL of the extracted-xylan is similarwith Km5.6044mg/mL of oak xylan.Comparing with the optimaltemperature of DSM10635xylanase which used birch xylan and theextracted-xylan as substrates，the optimal temperature was about70℃.Thenusing corn cob as media did solid state fermentation by T.lauginosus DSM10635.The conditions were at50℃,dry corncob/water ratio was1/3.3,thexylanse production was achieved16255.565IU/g.The xylanase waspurificated by using the ammonium sulfate gradient precipitation andHIC.The pure xylanase activity was greater than10000IU/g.And the resultof SDS-PAGE showed the single band.Finally,the corncob xylan washydrolyzed by the purified xylanase,the results were detected by TLC andHPLC.12h showed the best time to hydrolyze the extracted-xylan.Thefurther text method was HPLC.The xylobiose concentration is4.346mg/mLand xyltriose concentration is0.658mg/mL.There were two single peaksshowed in the image of HPLC,it meant that the separation of xylbiose andxyltriose is good.