Jiang Xianzhang, Du Jiawen, He Ruonan, Zhang Zhengying, Qi Feng, Huang Jianzhong, Qin Lina
National Joint Engineering Research Center of Industrial Microbiology and Fermentation Technology, College of Life Sciences, Fujian Normal University, Fuzhou, China.
Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, College of Life Sciences, Fujian Normal University, Fuzhou, China.
Front Microbiol. 2020 Jul 14;11:1633. doi: 10.3389/fmicb.2020.01633. eCollection 2020.
Lignocellulose is an abundant waste resource and has been considered as a promising material for production of biofuels or other valuable bio-products. Currently, one of the major bottlenecks in the economic utilization of lignocellulosic materials is the cost-efficiency of converting lignocellulose into soluble sugars for fermentation. One way to address this problem is to seek superior lignocellulose degradation enzymes or further improve current production yields of lignocellulases. In the present study, the lignocellulose degradation capacity of a thermophilic fungus was firstly evaluated and compared to that of the biotechnological workhorse The data demonstrated that compared to displayed substantially higher cellulose-utilizing efficiency with relatively lower production of cellulases, indicating that better cellulases might exist in . Comparison of the protein secretome between and showed that the secreted protein categories were quite different in these two species. In addition, to prove that cellulases in had better enzymatic properties, the major cellulase cellobiohydrolase I (CBH1) from and were firstly characterized, respectively. The data showed that the specific activity of CBH1 was about 4.5-fold higher than CBH1 in a wide range of temperatures and pH. To explore whether increasing CBH1 activity in could contribute to improving the overall cellulose-utilizing efficiency of , gene was replaced with gene by integration of gene into gene locus. The data surprisingly showed that this gene replacement not only increased the cellobiohydrolase activities by around 4.1-fold, but also resulted in stronger induction of other cellulases genes, which caused the filter paper activities, Azo-CMC activities and β-glucosidase activities increased by about 2.2, 1.9, and 2.3-fold, respectively. The study here not only provided new resources of superior cellulases genes and new strategy to improve the cellulase production in , but also contribute to opening the path for fundamental research on
木质纤维素是一种丰富的废弃资源，被认为是生产生物燃料或其他有价值生物产品的有前景的材料。目前，木质纤维素材料经济利用的主要瓶颈之一是将木质纤维素转化为可发酵的可溶性糖的成本效益。解决这个问题的一种方法是寻找优良的木质纤维素降解酶或进一步提高目前木质纤维素酶的产量。在本研究中，首先评估了一种嗜热真菌的木质纤维素降解能力，并与生物技术中常用的菌种进行了比较。数据表明，与常用菌种相比，该嗜热真菌表现出更高的纤维素利用效率和相对较低的纤维素酶产量，这表明该嗜热真菌可能存在更好的纤维素酶。对该嗜热真菌和常用菌种的蛋白质分泌组进行比较，结果表明这两个物种分泌的蛋白质类别有很大差异。此外，为了证明该嗜热真菌中的纤维素酶具有更好的酶学性质，分别对该嗜热真菌和常用菌种的主要纤维素酶纤维二糖水解酶I（CBH1）进行了表征。数据显示，在广泛的温度和pH范围内，该嗜热真菌CBH1的比活性比常用菌种CBH1高约4.5倍。为了探究提高该嗜热真菌中CBH1的活性是否有助于提高其整体纤维素利用效率，通过将基因整合到该嗜热真菌的基因位点，用基因替换了基因。令人惊讶的是，数据显示这种基因替换不仅使纤维二糖水解酶活性提高了约4.1倍，还导致其他纤维素酶基因的诱导增强，从而使滤纸酶活性、偶氮羧甲基纤维素酶活性和β-葡萄糖苷酶活性分别提高了约2.2倍、1.9倍和2.3倍。本研究不仅提供了优良纤维素酶基因的新资源和提高该嗜热真菌纤维素酶产量的新策略，也为相关基础研究开辟了道路。
