Background Xylanase is one of the most extensively used biocatalysts for biomass degradation. However, its low catalytic efficiency and poor thermostability limit 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 bioenergy. Results Using fragment replacement, we improved the catalytic performance and thermostability of a GH10 xylanase, XylE. Of the ten hybrid enzymes obtained, seven showed xylanase activity. Substitution of fragments, M3, M6, M9, and their combinations enhanced the catalytic efficiency (by 2.4- to fourfold) as well as the specific activity (by 1.2- to 3.3-fold) of XylE. The hybrids, XylE-M3, XylE-M3/M6, XylE-M3/M9, and XylE-M3/M6/M9, showed enhanced thermostability, as observed by the increase in the T 50 (3-4.7 °C) and T m (1.1-4.7 °C), and extended t 1/2 (by 1.8-2.3 h). In addition, the synergistic effect of the mutant xylanase and cellulase on the degradation of mulberry bark showed that treatment with both XylE-M3/M6 and cellulase exhibited the highest synergistic effect. In this case, the degree of synergy reached 1.3, and the reducing sugar production and dry matter reduction increased by 148% and 185%, respectively, compared to treatment with only cellulase. Conclusions This study provides a successful strategy to improve the catalytic properties and thermostability of enzymes. We identified several xylanase candidates for applications in bioenergy and biorefinery. Synergistic degradation experiments elucidated a possible mechanism of cellulase inhibition by xylan and xylo-oligomers.

中文翻译：

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GH10木聚糖酶的催化活性和热稳定性的改进及其与纤维素酶对生物质的协同降解。

背景木聚糖酶是用于生物质降解的最广泛使用的生物催化剂之一。但其催化效率低、热稳定性差限制了其应用。因此，改善木聚糖酶的性质以实现木质纤维素生物质与纤维素酶的协同降解在生物能源领域具有重要意义。结果使用片段替换，我们提高了 GH10 木聚糖酶 XylE 的催化性能和热稳定性。在获得的十种杂合酶中，七种显示出木聚糖酶活性。片段、M3、M6、M9 及其组合的取代增强了 XylE 的催化效率（2.4 至 4 倍）以及比活性（1.2 至 3.3 倍）。杂种 XylE-M3、XylE-M3/M6、XylE-M3/M9 和 XylE-M3/M6/M9 显示出增强的热稳定性，正如 T 50 (3-4.7 °C) 和 T m (1.1-4.7 °C) 的增加所观察到的，并且 t 1/2 延长（1.8-2.3 h）。此外，突变木聚糖酶和纤维素酶对桑树皮降解的协同作用表明，XylE-M3/M6和纤维素酶处理的协同作用最高。在这种情况下，协同程度达到1.3，与仅使用纤维素酶处理相比，还原糖产量和干物质减少量分别增加了148%和185%。结论 本研究为提高酶的催化性能和热稳定性提供了一种成功的策略。我们确定了几种可用于生物能源和生物精炼的木聚糖酶候选物。协同降解实验阐明了木聚糖和木寡聚体抑制纤维素酶的可能机制。