Alkaline incubation improves the saccharification of poplar after sodium chlorite pretreatment with ultra-low cellulase loading

The limitation of xylan hydrolysis is a characteristic problem of sodium chlorite (SC) pretreatment, which greatly restricted the saccharification of SC-pretreated lignocelluloses. In this work, the effect of alkali incubation on the xylan hydrolysis of SC-pretreated poplar was investigated. SC pretreatment of poplar removed 84.7% lignin, which yielded 71.2% glucose and 60.0% xylose under a cellulase loading of 20 filter paper units (FPU)/g dry matter (DM). The subsequent alkali incubation reduced the acetyl group, surface lignin, and surface chlorine contents of SC-pretreated poplar. Glucose and xylose yields were increased to 92.4% and 86.3%, respectively, by incubating SC-pretreated samples with 1.0% NaOH at 50 degrees C for 1 h using a cellulase loading of 2 FPU/g DM. Both Tween 80 and xylanase improved the enzymatic hydrolysis yield of SC-pretreated poplar. Alkali incubation showed a 9-fold decrease in cellulase loading and increased the xylose yield of SC-pretreated poplar by 119.8%. This work overcame the limitation of xylan hydrolysis in sodium chlorite-pretreated lignocelluloses and represented a novel method to efficiently saccharification of poplar with ultra-low cellulase loading. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Alkali incubation improved the xylan hydrolysis efficiency of SC-pretreated poplar, leading to higher yields of glucose and xylose. The reduction of lignin and chlorine contents, as well as the decrease in cellulase loading, contributed to the increased sugar yields.