Enhanced enzymatic hydrolysis of wheat straw via a combination of alkaline hydrogen peroxide and lithium chloride/N,N-dimethylacetamide pretreatment

Abstract

The aim of this work was to enhance enzymatic hydrolysis of wheat straw (WS) via a combination of alkaline hydrogen peroxide (AHP) and lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) pretreatment. The physicochemical structural changes of pretreated WS were systematically characterized. Furthermore, the hydrolytic efficiency and synergistic action between xylanase and cellulase in the enzymatic hydrolysis of pretreated WS were investigated. Results suggested that AHP-LiCl/DMAc pretreatment enhanced the enzymatic hydrolysis efficiency dramatically by effective delignification and completely deconstructing the crystalline structure of cellulose in WS. The maximum cellulose and xylan enzymatic hydrolysis efficiencies of AHP-LiCl/DMAc treated WS reached up to 97.49% and 87.80%, respectively, by adding cellulase and xylanase simultaneously. The disruption of hydrogen bond in cellulose and xylan reduced the synergistic effect between xylanase and cellulase during enzymatic hydrolysis of AHP-LiCl/DMAc pretreated WS, especially for cellulose hydrolysis. The hydrogen bond present in cellulose and xylan is one of the key factors on determining the synergistic action of xylanase and cellulase, which also plays an important role in enzymatic saccharification process. Overall, this study provides a promising pretreatment strategy for the efficient enzymatic hydrolysis of WS into fermentable sugars.