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, School of Life & Health Sciences, Hubei University of Technology, Wuhan, 430068, China; College of Plant Science & Technology, Huazhong Agricultural University, Wuhan 430070, China.
College of Life Science & Technology, Huazhong Agricultural University, Wuhan, 430070, China.
Int J Biol Macromol. 2024 Oct;278(Pt 1):134524. doi: 10.1016/j.ijbiomac.2024.134524. Epub 2024 Aug 5.
Crop straws provide enormous lignocellulose resources transformable for sustainable biofuels and valuable bioproducts. However, lignocellulose recalcitrance basically restricts essential biomass enzymatic saccharification at large scale. In this study, the mushroom-derived cellobiohydrolase (LeGH7) was introduced into Trichoderma reesei (Rut-C30) to generate two desirable strains, namely GH7-5 and GH7-6. Compared to the Rut-C30 strain, both engineered strains exhibited significantly enhanced enzymatic activities, with β-glucosidases, endocellulases, cellobiohydrolases, and xylanase activities increasing by 113 %, 140 %, 241 %, and 196 %, respectively. By performing steam explosion and mild alkali pretreatments with mature straws of five bioenergy crops, diverse lignocellulose substrates were effectively digested by the crude enzymes secreted from the engineered strains, leading to the high-yield hexoses released for bioethanol production. Notably, the LeGH7 enzyme purified from engineered strain enabled to act as multiple cellulases and xylanase at higher activities, interpreting how synergistic enhancement of enzymatic saccharification was achieved for distinct lignocellulose substrates in major bioenergy crops. Therefore, this study has identified a novel enzyme that is active for simultaneous hydrolyses of cellulose and xylan, providing an applicable strategy for high biomass enzymatic saccharification and bioethanol conversion in bioenergy crops.
农作物秸秆提供了巨大的木质纤维素资源，可转化为可持续的生物燃料和有价值的生物制品。然而，木质纤维素的顽固性在很大程度上限制了必要的生物质酶解糖化在大规模生产中的应用。在本研究中，蘑菇来源的纤维二糖水解酶（LeGH7）被引入里氏木霉（Rut-C30）中，生成了两个理想的菌株，即 GH7-5 和 GH7-6。与 Rut-C30 菌株相比，这两个工程菌株的酶活性都显著增强，β-葡萄糖苷酶、内切纤维素酶、纤维二糖水解酶和木聚糖酶的活性分别提高了 113%、140%、241%和 196%。通过对五种生物能源作物的成熟秸秆进行蒸汽爆破和温和碱预处理，工程菌株分泌的粗酶有效地消化了各种木质纤维素底物，从而获得了可用于生产生物乙醇的高产量己糖。值得注意的是，从工程菌株中纯化出的 LeGH7 酶能够以更高的活性充当多种纤维素酶和木聚糖酶，解释了协同增强对主要生物能源作物中不同木质纤维素底物的酶解糖化作用的机制。因此，本研究鉴定出了一种新型的酶，它可以同时水解纤维素和木聚糖，为生物能源作物中高生物质酶解糖化和生物乙醇转化提供了一种可行的策略。
