| 论文题目: | Effects of salts on activity of halophilic cellulase with glucomannanase activity isolated from alkaliphilic and halophilic Bacillus sp BG-CS10 |
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| 作者: | Zhang, GM; Li, SY; Xue, YF; Mao, LW; Ma, YH |
| 联系作者: | Ma, YH |
| 刊物名称: | EXTREMOPHILES |
| 期: | 1 |
| 卷: | 16 |
| 页: | 35-43 |
| 年份: | 2012 |
| 影响因子: | 2.941 |
| 论文下载: | |
| 摘要: | Alkaliphilic and halophilic Bacillus sp. BG-CS10 was isolated from Zabuye Salt Lake, Tibet. The gene celB, encoding a halophilic cellulase was identified from the genomic library of BG-CS10. CelB belongs to the cellulase superfamily and DUF291 superfamily, with an unknown function domain and less than 58% identity to other cellulases in GenBank. The purified recombinant protein (molecular weight: 62 kDa) can hydrolyze soluble cellulose substrates containing beta-1,4-linkages, such as carboxylmethyl cellulose and konjac glucomannan, but has no exoglucanase and beta-glucosidase activities. Thus, CelB is a cellulase with an endo mode of action and glucomannanase activity. Interestingly, the enzyme activity was increased approximately tenfold with 2.5 M NaCl or 3 M KCl. Furthermore, the optimal temperatures were 55A degrees C with 2.5 M NaCl and 35A degrees C without NaCl, respectively. This indicates that NaCl can improve enzyme thermostability. The K (m) and k (cat) values of CelB for CMC with 2.5 M NaCl were 3.18 mg mL(-1) and 26 s(-1), while the K (m) and k (cat) values of CelB without NaCl were 6.6 mg mL(-1) and 2.1 s(-1). Thus, this thermo-stable, salt and pH-tolerant cellulase is a promising candidate for industrial applications, and provides a new model to study salt effects on the structure of protein. |
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