Sun Ming-zhe, Zheng Hong-chen, Meng Ling-cai, Sun Jun-she, Song Hui, Bao Yun-juan, Pei Hai-sheng, Yan Zheng, Zhang Xiu-qing, Zhang Jing-sheng, Liu Yi-han, Lu Fu-ping
Key Laboratory of Industrial Fermentation Microbiology, Education Ministry of China, No. 29, 13 Main Street, Tianjin Economic and Technological Development Zone, Tianjin, 300457, China.
Biotechnol Lett. 2015 Sep;37(9):1877-86. doi: 10.1007/s10529-015-1857-6. Epub 2015 May 21.
To acquire a thermostable xylanase, that is suitable for xylooligosaccharide production from pretreated corncobs, the metagenomic method was used to obtain the gene from an uncultured environmental microorganism.
A thermostable xylanase-encoding gene (xyn10CD18) was cloned directly from the metagenomic DNA of cow dung compost. When xyn10CD18 was expressed in Bacillus megaterium MS941, extracellular xylansae activity at 106 IU/ml was achieved. The purified recombinant Xyn10CD18 was optimally active at pH 7 and 75 °C as measured over 10 min. It retained over 55% of its initial activity at 70 °C and pH 7 after 24 h. Its action on birchwood xylan for 18 h liberated xylooligosaccharides with 2°-4° of polymerization, with xylobiose and xylotetraose as the main products. When pretreated corncobs were hydrolyzed by Xyn10CD18 for 18 h, the xylooligosaccharides (DP 2-4) products increased to 80% and the xylose was just increased by 3%.
Xyn10CD18 is a thermostable endoxylanase and is a promising candidate for biomass conversion and xylooligosaccharide production.
为获得一种适用于从预处理玉米芯生产低聚木糖的耐热木聚糖酶，采用宏基因组学方法从未培养的环境微生物中获取该基因。
从牛粪堆肥的宏基因组DNA中直接克隆到一个耐热木聚糖酶编码基因（xyn10CD18）。当xyn10CD18在巨大芽孢杆菌MS941中表达时，胞外木聚糖酶活性达到106 IU/ml。纯化后的重组Xyn10CD18在pH 7和75℃下保温10分钟时活性最佳。在70℃和pH 7条件下处理24小时后，仍保留其初始活性的55%以上。它作用于桦木木聚糖18小时后释放出聚合度为2-4的低聚木糖，主要产物为木二糖和木四糖。当用Xyn10CD18水解预处理玉米芯18小时时，低聚木糖（聚合度2-4）产物增加到80%，木糖仅增加3%。
Xyn10CD18是一种耐热的内切木聚糖酶，是生物质转化和低聚木糖生产的有潜力的候选酶。
