An alkali-tolerant xylanase produced by the newly isolated alkaliphilic Bacillus pumilus from paper mill effluent
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An alkaline active xylanase, XynBYG, was purified from an alkaliphilic Bacillus pumilus BYG, which was newly isolated from paper mill effluent. It had an optimum pH of 8.0–9.0, and showed good stability after incubated at pH 9.0 for 120 min. The optimum temperature for the activity was 50°C, and the enzyme retained below 55% of its original activity for 30 min at 55°C. The gene coding for XynBYG consists of 687 bp and encodes 229 amino acids. Similarity analysis indicated that XynBYG belong to family 11 glycosyl hydrolases. Site-directed mutagenesis was performed to replace five sites (Tyr/Ser) to Arg/Glu and the results demonstrated that the optimum temperature of the mutant Y7 (S39R-T146E) increased 5°C and the half-life of inactivation (T1/2) at 60 and 65°C was 1 h and 25 min, respectively. Thus, it provides a potential xylanase that can meet the harsh conditions in the industrial applications.
KeywordsAlkali-tolerant xylanase Bacillus pumilus Expression Site-directed mutagenesis Thermostability
The financial supplement of national New Productions Project from science and technology ministry (P.R. China) is gratefully acknowledged.
- 2.Sunna A, Gibbs MD, Bergquist PL (2000) A novel thermostable multidomain 1, 4-β-xylanase from ‘Caldibacillus cellulovorans’ and effect of its xylan-binding domain on enzyme activity. Microbiol 146:2947–2955Google Scholar
- 7.Bansod SM, Rele MV (1998) Alkaline xylanase from an alkalotolerant Cephalosporium sp.: characteristics. J Biochem Mol Biol Biophys 2:121–128Google Scholar
- 14.Georis J, de Lemos Esteves F, Lamotte-Brasseur J, Bougnet V, Devreese B, Giannotta F, Granier B, Frere JM (2000) An additional aromatic interaction improves the thermostability and thermophilicity of a mesophilic family 11 xylanase: structural basis and molecular study. Protein Sci 9:466–475CrossRefPubMedGoogle Scholar
- 22.Smibert RM, Krieg NR (1981) Systematics: general characterization. In: Manual of methods for general bacteriology, pp 409–443Google Scholar
- 23.Sambrook J, Fritsch EF, Maniatis T (1989) Molecular cloning: a laboratory manual, 2nd edn. Cold Spring Harbor Laboratory, Cold Spring HarborGoogle Scholar