Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, People's Republic of China.
J Agric Food Chem. 2013 Jul 17;61(28):6880-9. doi: 10.1021/jf4001296. Epub 2013 Jul 3.
This study identified two family-11 xylanase genes (xynC81 and xynC83) in Achaetomium sp. Xz-8, a thermophilic strain from a desert area with substantial xylanase activity, and successfully expressed them in Pichia pastoris . Their deduced amino acid sequences showed the highest identity of ≤90% to known fungal xylanases and of ≤62% with each other. The purified recombinant xylanases showed optimal activities at pH 5.5 and 60-65 °C and exhibited stability over pH 5.0-10.0 and temperatures at 55 °C and below. XynC81 had high catalytic efficiency (6082 mL/s/mg), and XynC83 was favorable for xylooligosaccharide production. Under simulated mashing conditions, combination of XynC83 and a commercial β-glucanase improved the filtration rate by 34.76%, which is much better than that of Novozymes Ultraflo (20.71%). XynC81 and XynC83 had a synergistic effect on viscosity reduction (7.08%), which is comparable with that of Ultraflo (8.47%). Thus, XynC81 and XynC83 represent good candidates for application in the brewing industry.
本研究在一株嗜热真菌 Achaetomium sp. Xz-8 中鉴定出两个家族 11 木聚糖酶基因（xynC81 和 xynC83），该真菌来自沙漠地区，具有较高的木聚糖酶活性，并在毕赤酵母中成功表达。它们的推导氨基酸序列与已知真菌木聚糖酶的最高同源性≤90%，彼此之间的同源性≤62%。纯化的重组木聚糖酶在 pH5.5 和 60-65°C 下显示出最佳活性，并在 pH5.0-10.0 和 55°C 及以下的温度下表现出稳定性。XynC81 具有较高的催化效率（6082 mL/s/mg），而 XynC83 有利于生产木寡糖。在模拟糖化条件下，XynC83 与一种商业β-葡聚糖酶的组合可将过滤速度提高 34.76%，明显优于诺维信的 Ultraflo（20.71%）。XynC81 和 XynC83 对降低黏度有协同作用（7.08%），与 Ultraflo（8.47%）相当。因此，XynC81 和 XynC83 是应用于酿造工业的良好候选者。
