A novel efficient β-glucanase from a paddy soil microbial metagenome with versatile activities. Issue 1 (December 2016)

• Record Type: Journal Article
• Authors: Zhou, Yu; Wang, Xu; Wei, Wei; Xu, Jimin; Wang, Wei; Xie, Zhongwen; Zhang, Zhengzhu; Jiang, Hongchen; Wang, Qi; Wei, Chaoling
• Is Part Of: Biotechnology for biofuels. Volume 9:Issue 1(2016)
• Page Start: 1
• Page End: 14
• Publication Date: 2016-12
• Subjects: Metagenomic library -- Versatile β-glucanase -- Glycoside hydrolase family 9 -- Transglycosylation -- Endoglucanase -- Exoglucanases; Biotechnology -- Periodicals; Biomass energy -- Periodicals; Energy-Generating Resources -- Periodicals; 662.88
• DOI: 10.1186/s13068-016-0449-6
• Languages: English
• ISSNs: 1754-6834

Abstract

Abstract Background Cellulose, an abundant and renewable polysaccharides, constitutes the largest resource for bioconversion of biofuels. Plant polysaccharides hydrolysis is catalyzed by cellulases, which include endoglucanases, exoglucanases, and β-glucosidases. Converting cellulose and hemicellulose to short chains of oligosaccharides by endo-/exoglucanases is the key step for biofuel transformation. Intriguingly, β-glucanases with transglycosylation activity not only can relieve product inhibition of glucan hydrolysis but also has potential application as biocatalysts for functional materials. Results Here, a metagenomic fosmid library was constructed from a paddy soil for cellulase screening. One purified clone showing carboxymethylcellulase activity was isolated, and the complete β-glucanase gene (umcel9y -1 ) was cloned and overexpressed inEscherichia coli . Phylogenetic analysis indicated that β-glucanase Umcel9y-1 belonged to the theme C of glycoside hydrolase family 9. Amino acids sequence showed 58.4 % similarity between Umcel9y-1 and its closest characterized reference, cellulase Cel01. Biological characterization showed that Umcel9y-1 was an efficient endoglucanase and also exhibited high activities of exoglucanase and transglycosylation. The transglycosylation products of Umcel9y-1 including sophorose, laminaribiose, and gentiobiose, and transglycosylation was detected under all activated conditions. The order of catalytic efficiency for polysaccharides, cellooligosaccharides, and aryl-β-glycosides was p-nitrophenol-D-cellobioside, barley glucan, cellopentaose, cellotetraose, cellotriose, hydroxyethylcellulose, cellohexose, laminarin, and carboxymethylcellulose, respectively. The barley glucan was the optimal polysaccharides for Umcel9y-1 withK m andK cat /K m values of 13.700 mM and 239.152 s−1 mM−1, respectively. Conclusion Biological characterizations of recombinant Umcel9y-1 showed that the versatile β-glucanase had efficient endoglucanase activity to barley glucan and also exhibited high activities of exoglucanase and transglycosylation. The optimum conditions of recombinant Umcel9y-1 was pH 6.5–7.0 at 37 °C with predominant halotolerance and high-thermal stability. These results indicate that the novel metagenomic-derived β-glucanase may be a potent candidate for industrial applications.