Key Laboratory of Fermentation Engineering (Ministry of Education), National "111" Center for Cellular Regulation & Molecular Pharmaceutics, Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, College of Biotechnology & Food Science, Hubei University of Technology, Wuhan 430068, China; Biomass & Bioenergy Research Centre, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan 430070, China; School of Basic Medical Sciences, Hubei University of Medicine, Shiyan 442000, China.
Biomass & Bioenergy Research Centre, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan 430070, China; College of Life Science & Technology, Huazhong Agricultural University, Wuhan 430070, China.
Bioresour Technol. 2023 May;376:128844. doi: 10.1016/j.biortech.2023.128844. Epub 2023 Mar 10.
In this study, bacterial BsEXLE1 gene was overexpressed into T. reesei (Rut-C30) to generate a desirable engineered TrEXLX10 strain. While incubated with alkali-pretreated Miscanthus straw as carbon source, the TrEXLX10 secreted the β-glucosidases, cellobiohydrolases and xylanses with activities raised by 34%, 82% and 159% compared to the Rut-C30. Supplying EXLX10-secreted crude enzymes and commercial mixed-cellulases for two-step lignocellulose hydrolyses of corn and Miscanthus straws after mild alkali pretreatments, this work measured consistently higher hexoses yields released by the EXLX10-secreted enzymes for synergistic enhancements of biomass saccharification in all parallel experiments examined. Meanwhile, this study detected that the expansin, purified from EXLX10-secreted solution, was of exceptionally high binding activities with wall polymers, and further determined its independent enhancement for cellulose hydrolysis. Therefore, this study raised a mechanism model to highlight EXLX/expansin dual-activation roles for both secretion of stable biomass-degradation enzymes at high activity and biomass enzymatic saccharification in bioenergy crops.
在这项研究中，细菌 BsEXLE1 基因被过表达到里氏木霉（Rut-C30）中，以产生理想的工程 TrEXLX10 菌株。当用碱预处理的芒草秸秆作为碳源培养时，与 Rut-C30 相比，TrEXLX10 分泌的β-葡萄糖苷酶、纤维二糖水解酶和木聚糖酶的活性分别提高了 34%、82%和 159%。在用温和碱预处理后对玉米和芒草秸秆进行两步木质纤维素水解时，提供 EXLX10 分泌的粗酶和商业混合纤维素酶，本工作在所有平行实验中均一致地测量到由 EXLX10 分泌的酶释放出更高的己糖产率，从而协同增强生物质的糖化。同时，本研究发现，从 EXLX10 分泌液中纯化的扩张蛋白与壁聚合物具有极高的结合活性，并进一步确定其对纤维素水解具有独立的增强作用。因此，本研究提出了一个机制模型，以强调 EXLX/扩张蛋白双重激活作用，既能在高活性下分泌稳定的生物质降解酶，又能促进生物能源作物的生物质酶解糖化。
