Cloning, expression, and characterization of a novel alkali-tolerant xylanase from alkaliphilic Bacillus sp SN5----中国科学院微生物研究所

科研成果

论文题目:	Cloning, expression, and characterization of a novel alkali-tolerant xylanase from alkaliphilic Bacillus sp SN5
作者:	Bai Wenqin , Xue Yanfen , Zhou Cheng , and Ma Yanhe*.
联系作者:
刊物名称:	Biotechnology and Applied Biochemistry
期:	62
卷:	2
页:	208-217
年份:	2015
影响因子:	1.585
论文下载:	http://onlinelibrary.wiley.com/doi/10.1002/bab.1265/abstract;jsessionid=CE6546CFDF00895034B6DCE5DEC941BD.f03t02
摘要:	A xylanase gene (xyn11A) was cloned from the genomic library of alkalophilic Bacillus sp. SN5. It encoded a polypeptide of 366 amino acids, consisting of a family 11 glycoside hydrolase, a short linker region, and a family 36 carbohydrate-binding module (CBM). The intact xylanase Xyn11A and the CBM-linker-truncated Xyn11A-LC were expressed in Escherichia coli BL21 (DE3). Both purified recombinant proteins exhibited the highest activity at 55 degrees C. The optimal pH for Xyn11A activity was 7.5, whereas Xyn11A-LC showed a broad pH profile (>80% activity at pH 5.5-8.5) with optimal activity at pH 5.5 and 7.5-8.0. They had high alkali tolerance, retaining over 80% residual activity after preincubation at pH 8.5-11.0 at 37 degrees C for 1H. Xyn11A-LC showed better thermal stability, lower affinity, and lower catalytic activity to insoluble xylan than Xyn11A, whereas its specific activity for soluble beechwood xylan (4,511.9U/mg) was greater than that of Xyn11A (3,136.4U/mg). These results implied that the CBM of Xyn11A could change the enzymatic properties and play a role in degrading insoluble xylan. Xyn11A-LC is a family 11 alkali-tolerant cellulase-free xylanase with high specific activity, which qualifies it as a potential candidate for industrial applications, especially in the paper industry. (C) 2014 International Union of Biochemistry and Molecular Biology, Inc.