title: Characterization of a novel xylanase gene from rumen content of Hu sheep.
abstract: A novel xylanase gene, xyn-lxy, was cloned from a metagenomic fosmid library, which was previously constructed from the rumen contents of Hu sheep and was functionally characterized in Escherichia coli. The open reading frame was composed of 1923 bp and encoded for 640 amino acids, including a catalytic domain of glycosyl hydrolase family 10 and carbohydrate-binding module 9. The gene showed 97 % identity with uncultured bacterium Contig1552 but low similarity with xylanases from known cellulolytic-degrading microorganisms in the rumen. The recombinant XYN-LXY showed a specific activity of 664.7 U mg(-1). The optimal temperature and pH of the enzyme were 50 °C and 6.0, respectively. Specifically, XYN-LXY was exclusively activated by Mn(2+) among all of the cations and reducing agents tested in this study. An enzymatic hydrolysis assay revealed that XYN-LXY degraded birchwood xylan into xylooligosaccharide with a low degree of polymerization. After incubation for 4 h, the concentration of the dominant product, xylobiose, was 2.297 ± 0.175 mg ml(-1) (74.07 % of total product) followed by xylose with a concentration of 0.656 ± 0.010 mg ml(-1) (21.14 % of total product). The XYN-LXY exhibited deep degradation effects on the xylan substrate, which were rarely observed with endo-xylanase, making it a promising candidate for industrial application, especially in biofuel production.
authors.affiliation: Institute of Dairy Science, College of Animal Science, Zhejiang University, Yuhangtang Road 866#, Hangzhou, Zhejiang, 310058, China.|Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore City, 117604, Singapore.
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Institute of Dairy Science, College of Animal Science, Zhejiang University, Yuhangtang Road 866#, Hangzhou, Zhejiang, 310058, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Luo
authors.affiliation: Institute of Dairy Science, College of Animal Science, Zhejiang University, Yuhangtang Road 866#, Hangzhou, Zhejiang, 310058, China.
authors.forename: Bo
authors.initials: B
authors.lastname: He
authors.affiliation: Beijing Key Laboratory for Dairy Cow Nutrition, Beijing University of Agriculture, Beinong Road 7, Huilongguan, Changping District, Beijing, 102206, China. kjxnb@vip.sina.com.
authors.forename: Lin-Shu
authors.initials: LS
authors.lastname: Jiang
authors.affiliation: Institute of Dairy Science, College of Animal Science, Zhejiang University, Yuhangtang Road 866#, Hangzhou, Zhejiang, 310058, China.
authors.forename: Jian-Xin
authors.initials: JX
authors.lastname: Liu
authors.affiliation: Institute of Dairy Science, College of Animal Science, Zhejiang University, Yuhangtang Road 866#, Hangzhou, Zhejiang, 310058, China. jiakunwang@zju.edu.cn.
authors.forename: Jia-Kun
authors.initials: JK
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D029662:Betula / Q000737:chemistry; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics; D015723:Gene Library; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008670:Metals / Q000494:pharmacology; D008969:Molecular Sequence Data; D019163:Reducing Agents / Q000494:pharmacology; D012417:Rumen / Q000201:enzymology*; D012756:Sheep; D013696:Temperature; D014934:Wood / Q000737:chemistry; D014990:Xylans / Q000378:metabolism
chemical_list: D008670:Metals; D019163:Reducing Agents; D014990:Xylans; D043364:Endo-1,4-beta Xylanases
keywords: Enzyme properties; Hydrolysis; Rumen; Xylanase; Xylooligosaccharide