Enhancing Effect Of Lignosulfonate And Long-chain Fatty Alcohols On The Enzymatic Hysrolysis Of Xylan And Its Application

Lignocellulosic biomass as an abundant sustainable source for the production of bioenergy and biomaterials, has received extensive research and investment with the growing depletion of fossil energy. Xylan is a major structural polysaccharide in plant cell walls, and it is the most abundant hemicelluloses in nature which exists widely in agroforestry wastes such as corncob, straw, bagasse and wood shavings. Xylan can be converted to bio-fuels, xylitol and furfural through the sugar platform. Corncob is large output and low price in China, the object of the study is to improve the enzymatic hydrolysis efficiency of xylan in corncob substrate by adding sodium lignosulfonate(SXSL), long-chain fatty alcohols(LFAs) and non-ionic surfactants(PEG4600,NPE). The effects of additives on the nonproductive adsorption of xylanase on cellulose and lignin were further investigated by UV-Vis Spectrophotometer and quartz crystal microbalance with dissipation monitoring(QCM-D), to reveal the underlying mechanism of enhancing the enzymatic hydrolysis of lignocelluloses. An efficient strategy was developed to improve the enzymatic hydrolysis of xylan in corncob by adding lignosulfonate and cellulase in combination. The results were summarized as follows:1. SXSL, LFAs, PEG4600 and NPE could enhance the enzymatic hydrolysis of xylan, and the compound of SXSL and LFAs have synergies on the enzymatic hydrolysis. The addition of additives could enhance the enzymatic hydrolysis of xylan at different buffer p H, and show a good applicability in buffer p H range from 4 to 6. The enhancement of SXSL on enzymatic hydrolysis of xylan increased with the incrase of the SXSL dosage and the xylanase loading. The enhancement of LFAs, PEG4600 and NPE on enzymatic hydrolysis of xylan was stronger at high xylanase loading.2. The cellulose and lignin in corncob substrate could not only adsorb xylanase nonproductively, but also seriously reduce the accessibility of xylanase on xylan to impede the enzymatic hydrolysis of xylan, and cellulose had stronger inhibition on the enzymatic hydrolysis of xylan than lignin. The xylose yield at 72 h decreased from 48.3% to 30.1% and 37.0% by the addition of cellulose and lignin, respectively. SXSL and LFAs could reduce the negative effects of cellulose and lignin on the enzymatic hydrolysis of xylan, and the combination of SXSL and LFAs improved the enzymatic hydrolysis stronger than those used individually. SXSL could significantly reduce the nonproductive adsorptions of xylanase on lignin.3. Cellulase could break the plant cell wall structure of corncob and improve the enhancement of additives on the enzymatic hydrolysis of xylan and cellulose in corncob. The xylose yield of corncob at 72 h increased from 59.4% to 73.7% by adding the compound of 5 g/L SXSL and 0.01%(v/v) n-decanol, which was higher than that without cellulase and additives by 30.7%. Meanwhile, the glucose yield at 72 h of corncob increased from 45.8% to 62.3%.