Loop engineering of a thermostable GH10 xylanase to improve low-temperature catalytic performance for better synergistic biomass-degrading abilities

Shuai You,Jing Li,Fang Zhang,Zhi-Yuan Bai,Saidi Shittu,Richard-Ansah Herman,Wen-Xin Zhang,Jun Wang

doi:10.1016/j.biortech.2021.125962

Abstract

Lignocellulosic biorefining for producing biofuels poses technical challenges. It is usually conducted over a long time using heat, making it energy intensive. In this study, we lowered the energy consumption of this process through an optimized enzyme and pretreatment strategy. First, the dominant mutant M137E/N269G of Bispora sp. MEY-1XYL10C_ΔN was obtained by directed evolution with highcatalytic efficiency (970 mL/s∙mg)and specific activity (2090 U/mg)at 37 °C, and thermostability was improved (T50 increased by5 °C). After pretreatment with seawater immersionfollowing steam explosion,bagasse was co-treated with cellulase and M137E/N269G under mild conditions (37 °C), the resulting highest yield of fermentable sugars reached 219 µmol/g of bagasse,46% higher than that of the non-seawater treatment group, with the highest degree of synergy of 2.0. Pretreatment with seawater following steam explosion and synergistic hydrolysis through high activity xylanase and cellulase helped to achieve low energy degradation of lignocellulosic biomass.

Highlights

Xylanase can efficiently hydrolysis of hemicellulose, a barrier to the efficient saccharification of lignocellulose, into xylooligosaccharides and is widely used in the fields of feed, food and biomass utilization
In comparison with WT, MF53/53SL + N207G exhibited higher specific activity (2.9-fold; 2090 vs. 710 U/mg) and catalytic efficiency (2.8-fold; 1530 vs. 550 mL/s·mg) at 40°C, as well as higher thermostability
This study provided a successful strategy to improve the catalytic properties of enzymes and identified loop2 is a key functional area that affects the low-temperature catalytic efficiency of GH10 xylanase

Summary

Introduction

Xylanase can efficiently hydrolysis of hemicellulose, a barrier to the efficient saccharification of lignocellulose, into xylooligosaccharides and is widely used in the fields of feed, food and biomass utilization. High-temperature xylanase usually has low catalytic activity below 40°C, which limits its applications. Improving the properties of xylanases to enable synergistic degradation of lignocellulosic biomass with cellulase is of considerable significance in the field of bioconversion of lignocellulosic biomass

Methods

Results

Conclusion