The Effects Of Xylanase Component On Enzymatic Hydrolysis Of Poplar

This experiment investigated the effects of xylanase components on transformation rulesof cellulose and hemicellulose and the structure of enzyme hydrolyzate during enzymatichydrolysis process via poplar which was pretreated by xylanase single component assistedenzymatic hydrolysis of dilute alkali.Pretreatment of poplar under two different conditions, substrate A(120℃, treated by5%NaOH, then80℃, treated by5%NaOH and2%H2O2) and substrate B(80℃treated by5%NaOH and5%H2O2) were got respectively. The cellulose, hemicellulose and lignin contents ofsubstrate A and B were57.8,8.5,18.5%and47,9.7,24.8%, respectively.Four kinds of electrophoresis pure components were got when Richter xylanase wasseparated and edulcorated by gel filtration chromatography. Their molecular weights were98.73×10~3,21.62×10~3,19.67×10~3and2.85×10~3g/mol. They were xylosidase,Endo-xylanase XYNⅠand XYNⅡ, Exo-xylanase.The glucose yield of substrate A and substrate B were74.88and39.2%and the xyloseyield were62.3and57.5%after pretreated poplar hydrolysed by cellulose for72h. And afteradding xylosidase, Endo-xylanase XYNⅠand XYNⅡ, Exo-xylanase separately, the glucoseyield of substrate A were81.8,89.5,89.9and87.2%, get about7.0,14.62,15.02and12.32percentage point increase, the xylose yield were74.5,80.3,79.8and82.4%, get about12.2,18.0,17.5and20.1percentage point increase; the glucose yield of substrate B were45.3,62.7,57.8and47.7%, get about6.1,23.5,18.6and8.5percentage point increase, the xylose yieldwere61.7,70.1,77.1and85.5%, get about4.2,12.6,19.6and28.0percentage point increase.The results showed that xylanase can increase glucose yield and xylose yield of two substrates.Among them, XYNⅠand XYNⅡcan increase glucose yield obviously, Exo-xylanase canincrease xylose yield obviously. Four xylanase components have different effects on differentsubstrates. When the content of cellulose was low and the hemicellulose was higher,Exo-xylanase improved xylose yield more obviously which indicated that Exo-xylanase candigest hemicellulose better.The glucose yield of two substrates were90.8and54%, get about16and10percentagepoint increase, the xylose yield were65and81.6%, get about14and24.2percentage pointincrease by adding XYN Ⅰ and XYN Ⅱ mixed-component on the basis of the cellulose. Theresults showed that XYN Ⅰ and XYN Ⅱ mixed-component can digest hemicellulose better in thecase of the substrate with high content of hemicellulose.The enzymatic hydrolyzate was separated by gel filtration chromatography which wasadded XYN Ⅰ and XYN Ⅱ and xylo-oligosaccharides was analyzed by IR,1H and13C NMR.4-OMe-α-D-GlcpA was connected by C-O-C bond with (1→4)-β-D-Xylp in the products.(1→4)-β-D-Xylp was connected by glycosidic bond with lignin and formed Lignin-CarbohydrateComplexe(LCC).(1→4)-β-D-Xylp was connected by β-glycosidic bond;X2have one-CH2more than X1on the structure by the result of IR. The two products have little difference on thestructure by the result of1H and13C NMR and the specific differences are to be futher studied.