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Background Xylanase, an important accessory enzyme that acts in synergy with cellulase, is widely used to degrade lignocellulosic biomass. Thermostable enzymes with good catalytic activity at lower temperatures have great potential for future applications in the feed and fuel industries, which have distinct demands; however, the potential of the enzymes is yet to be researched. Results In this study, a structure-based semi-rational design strategy was applied to enhance the low-temperature catalytic performance of Bispora sp. MEY-1 XYL10C_∆N wild-type (WT). Screening and comparisons were performed for the WT and mutant strains. Compared to the WT, the mutant M53S/F54L/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, and also showed higher thermostability (the melting temperature and temperature of 50% activity loss after 30 min treatment increased by 7.7 °C and 3.5 °C, respectively). Compared with the cellulase-only treatment, combined treatment with M53S/F54L/N207G and cellulase increased the reducing sugar contents from corn stalk, wheat bran, and corn cob by 1.6-, 1.2-, and 1.4-folds, with 1.9, 1.2, and 1.6 as the highest degrees of synergy, respectively. Conclusions This study provides useful insights into the underlying mechanism and methods of xylanase modification for industrial utilization. We identified loop2 as a key functional area affecting the low-temperature catalytic efficiency of GH10 xylanase. The thermostable mutant M53S/F54L/N207G was selected for the highest low-temperature catalytic efficiency and reducing sugar yield in synergy with cellulase in the degradation of different types of lignocellulosic biomass. Graphic Abstract Supplementary Information The online version contains supplementary material available at 10.1186/s13068-021-02044-3., Highlights Key sites were proved to promote low-temperature catalytic efficiency of xylanase.Thermostable mutant with improved catalytic efficiency at 40 °C was obtained.Synergistic hydrolysis was dramatically improved between the mutant and cellulase.Agricultural wastes were converted into fermentable sugars by enzymolysis. Supplementary Information The online version contains supplementary material available at 10.1186/s13068-021-02044-3.

β-1,3-1,4-Glucanase is an indispensable biocatalyst in barley brewing industry for its crucial effect in reducing the viscosity of mash. However, the unsatisfactory thermostability greatly limited its application performance. In this study, structure-based surface charge engineering was conducted aiming at thermostability improvement of BisGlu16B, a highly active β-1,3-1,4-glucanase from Bispora sp. MEY-1. By applying the enzyme thermal stability system (ETSS), residues D47, D213, and D253 were inferred to be critical sites for thermal properties. Single (D47A, D213A, and D253A) and combination (D47A/D213A/D253A) mutants were generated and compared with BisGlu16B. Among all improved mutants, D47A/D213A/D253A outstanded in thermostability. In comparison with BisGlu16B, its T

Background 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. Therefore, 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. Results In this study, a structure-based rational design strategy was applied to enhance the low-temperature catalytic performance of XYL10C_∆N (WT). Screening and comparison were performed amoung the WT and mutants. 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 (with Tm and T50 increased by 7.7°C and 3.5°C, respectively). Meanwhile, comparing with cellulase-only treatment, the combination of MF53/53SL + N207G and cellulase increased the reducing sugar by 1.6-, 1.2-, and 1.4-folds for degradating corn stalk, wheat bran, and corn cob, with the highest degree of synergy of 1.9, 1.2, and 1.6, respectively. Conclusions 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. Several xylanase candidates for applications in feed and bioenergy applications were obtained. Synergistic degradation experiments elucidated a possible mechanism of cellulase inhibition by xylan during the hydrolysis of different types of biomass.