Bischoff Kenneth M, Rooney Alejandro P, Li Xin-Liang, Liu Siqing, Hughes Stephen R
U.S. Department of Agriculture, Agricultural Research Service, National Center for Agricultural Utilization Research, 1815 N. University St., Peoria, IL 61604, USA.
Biotechnol Lett. 2006 Nov;28(21):1761-5. doi: 10.1007/s10529-006-9153-0. Epub 2006 Aug 10.
Strains of thermophilic bacilli were screened for cellulolytic activity by gel diffusion assay on selective medium at 55 degrees C. Strain B-41361, identified as a strain of Bacillus licheniformis, displayed activity against carboxymethylcellulose. Zymogram analysis demonstrated several catalytically active polypeptides with the most prominent species having a mass of 37 kDa. The enzyme was purified 60-fold with a 17% yield and specific activity of 183 U/mg. The amino terminal sequence was homologous to members of glycoside hydrolase family 5. Optimal temperature was 65 degrees C (measured over 30 min), but the enzyme was most stable at 60 degrees C, retaining greater than 90% activity after one hour. The enzyme had a broad pH range, with maximal activity at pH 6.0, 75% maximal activity at pH 4.5, and 40% at pH 10. The enzyme hydrolyzed p-nitrophenylcellobioside, barley beta-glucan, and lichenan, but no activity was detected against avicel or acid-swollen cellulose.
在55摄氏度的选择性培养基上，通过凝胶扩散试验筛选嗜热芽孢杆菌菌株的纤维素分解活性。菌株B - 41361被鉴定为地衣芽孢杆菌，表现出对羧甲基纤维素的活性。酶谱分析显示有几种具有催化活性的多肽，其中最突出的一种分子量为37 kDa。该酶经过60倍纯化，产率为17%，比活性为183 U/mg。其氨基末端序列与糖苷水解酶家族5的成员同源。最适温度为65摄氏度（在30分钟内测定），但该酶在60摄氏度时最稳定，1小时后仍保留超过90%的活性。该酶具有较宽的pH范围，在pH 6.0时活性最高，在pH 4.5时为最大活性的75%，在pH 10时为40%。该酶能水解对硝基苯基纤维二糖、大麦β - 葡聚糖和地衣多糖，但对微晶纤维素或酸膨胀纤维素无活性。
