Characterization of a bifunctional xylanase/endoglucanase from yak rumen microorganisms
- 759 Downloads
A new gene, RuCelA, encoding a bifunctional xylanase/endoglucanase, was cloned from a metagenomic library of yak rumen microorganisms. RuCelA showed activity against xylan and carboxymethylcellulose (CMC), suggesting bifunctional xylanase/endoglucanase activity. The optimal conditions for xylanase and endoglucanase activities were 65°C, pH 7.0 and 50°C, pH 5.0, respectively. In addition, the presence of Co+ and Co2+ can greatly improve RuCelA's endoglucanase activity, while inhibits its xylanase activity. Further examination of substrate preference showed a higher activity against barley glucan and lichenin than against xylan and CMC. Using xylan and barley glucan as substrates, RuCelA displayed obvious synergistic effects with β-1,4-xylosidase and β-1,4-glucosidase. Generation of soluble oligosaccharides from lignocellulose is the key step in bioethanol production, and it is greatly notable that RuCelA can produce xylo-oligosaccharides and cello-oligosaccharides in the continuous saccharification of pretreated rice straw, which can be further degraded into fermentable sugars. Therefore, the bifunctional RuCelA distinguishes itself as an ideal candidate for industrial applications.
KeywordsBifunctional Metagenomic Xylanase Endoglucanase
This work was supported by Chinese High-tech Research and Development Program 2007AA021302.
- Buck GE, O'Hara LC, Summersgill JT (1992) Rapid simple method for treating clinical specimens containing Mycobacterium tuberculosis to remove DNA for polymerase chain reaction. J Clin Microbiol 30:1331–1334Google Scholar
- Chen HG, Yan X, Liu XY, Wang MD, Huang HM, Jia XC, Wang JA (2006) Purification and characterization of novel bifunctional xylanase, XynIII, isolated from Aspergillus niger A-25. J Microbiol Biotechnol 16:1132–1138Google Scholar
- Flint HJ, Martin J, Mcpherson CA, Daniel AS, Zhang JX (1993) A bifunctional enzyme with separate xylanase and β-(1, 3/1, 4)-glucanase domains, encoded by the XynD gene of Ruminococcus xavefaciens. J Bacteriol 175:2943–2951Google Scholar
- Lamed R, Bayer EA (1988) The cellulosome concept: exocellular enzyme reactor centers for efficient binding and cellulolysis. In: Aubert JP (ed) Biochemistry and genetics of cellulose degradation. Academic, London, pp 101–116Google Scholar
- Miller GL (1959) Use of dinitrosalicyclic acid reagent for determination of reducing sugar. Anal Chem 5:193–219Google Scholar
- Saitou N, Nei M (1987) The neighbor-joining method: a new method for reconstructing phylogenetic trees. Mol Biol Evol 4:406–425Google Scholar
- Teather RM, Wood PJ (1982) Use of congo red-polysaccharide interactions in enumeration and characterization of cellulolytic bacteria from the bovine rumen. Appl Environ Microbiol 43:777–780Google Scholar
- You C, Huang Q, Xue H, Xu Y, Lu H (2010) Potential hydrophobic interaction between two cysteines in interior hydrophobic region improves thermostability of a family 11 xylanase from Neocallimastix patriciarum. Biotechnol Bioeng 105:861–870Google Scholar