State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, 530004, Guangxi, People's Republic of China.
World J Microbiol Biotechnol. 2019 Oct 31;35(11):171. doi: 10.1007/s11274-019-2747-1.
Fungal endo-β-1,4-xylanases (endo-xylanases) can hydrolyze xylan into xylooligosaccharides (XOS), and have potential biotechnological applications for the exploitation of natural renewable polysaccharides. In the current study, we aimed to screen and characterize an efficient fungal endo-xylanase from 100 natural humus-rich soil samples collected in Guizhou Province, China, using extracted sugarcane bagasse xylan (SBX) as the sole carbon source. Initially, 182 fungal isolates producing xylanases were selected, among which Trichoderma sp. strain TP3-36 was identified as showing the highest xylanase activity of 295 U/mL with xylobiose (X2) as the main product when beechwood xylan was used as substrate. Subsequently, a glycoside hydrolase family 11 endo-xylanase, TXyn11A, was purified from strain TP3-36, and its optimal pH and temperature for activity against beechwood xylan were identified to be 5.0 and 55 °C, respectively. TXyn11A was stable across a broad pH range (3.0-10.0), and exhibited strict substrate specificity, including xylan from beechwood, wheat, rye, and sugarcane bagasse, with K and V values of 5 mg/mL and 1250 μmol/mg min, respectively, toward beechwood xylan. Intriguingly, the main product obtained from hydrolysis of beechwood xylan by TXyn11A was xylobiose, whereas SBX hydrolysis resulted in both X2 and xylotriose. Overall, these characteristics of the endo-xylanase TXyn11A indicate several potential industrial applications.
真菌内切-β-1,4-木聚糖酶（内切木聚糖酶）能够将木聚糖水解成木二糖（XOS），并且在利用天然可再生多糖方面具有潜在的生物技术应用。在本研究中，我们旨在从中国贵州省采集的 100 个天然腐殖质丰富的土壤样本中筛选和鉴定一种高效的真菌内切木聚糖酶，以提取的甘蔗渣木聚糖（SBX）为唯一碳源。最初，筛选出 182 株产木聚糖酶的真菌分离株，其中木霉（Trichoderma sp.）菌株 TP3-36 被鉴定为具有最高木聚糖酶活性，当以桦木木聚糖为底物时，其活性为 295 U/mL，主要产物为木二糖（X2）。随后，从菌株 TP3-36 中纯化出糖苷水解酶家族 11 内切木聚糖酶 TXyn11A，其对桦木木聚糖活性的最佳 pH 和温度分别为 5.0 和 55°C。TXyn11A 在较宽的 pH 范围内（3.0-10.0）稳定，并表现出严格的底物特异性，包括桦木木聚糖、小麦木聚糖、黑麦木聚糖和甘蔗渣木聚糖，对桦木木聚糖的 K 和 V 值分别为 5mg/mL 和 1250μmol/mg·min。有趣的是，TXyn11A 水解桦木木聚糖的主要产物是木二糖，而 SBX 水解的产物则是木二糖和木三糖。总的来说，内切木聚糖酶 TXyn11A 的这些特性表明它具有几种潜在的工业应用。
