1. Direct cloning, expression of a thermostable xylanase gene from the metagenomic DNA of cow dung compost and enzymatic production of xylooligosaccharides from corncob.
- Author
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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, and Lu, Fu-ping
- Subjects
MOLECULAR cloning ,HEAT stability in proteins ,OLIGOSACCHARIDE synthesis ,CATTLE manure microbiology ,METAGENOMICS ,GENE expression in mammals - Abstract
Objectives: 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. Results: 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 %. Conclusion: Xyn10CD18 is a thermostable endoxylanase and is a promising candidate for biomass conversion and xylooligosaccharide production. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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