African Journal of Biotechnology Vol. 5 (3), pp. 273-282, 2 February 2006   

ISSN 1684–5315 © 2006 Academic Journals        

Full Length Research Paper

Purification and biochemical properties of a new thermostable xylanase from symbiotic fungus, Termitomyces sp.

Betty Meuwiah Faulet¹, Sébastien Niamké^2,*, Jean Tia Gonnety¹ and Lucien Patrice Kouamé¹

¹Laboratoire de Biochimie et Technologie des Aliments de l’Unité de Formation et de Recherche en Sciences et Technologie des Aliments de l’Université d’Abobo-Adjamé, 02, BP 801 Abidjan 02, Côte d’Ivoire.

²Laboratoire de Biotechnologies, Filière Biochimie-Microbiologie de l’Unité de Formation et de Recherche en Biosciences de l’Université de Cocody-Abidjan, 22 BP 582 Abidjan 22, Côte d’Ivoire.

*Corresponding author. E-mail: niamkes@yahoo.fr Fax: (225) 20 37 81 18. Tel: (225) 07 84 64 09.

Accepted 6 December, 2005

A xylanase was purified from symbotic fungus, Termitomyces sp. by chromatography on columns of DEAE-Sepharose, CM-Sepharose, gel filtration and Phenyl-Sepharose. The preparation was shown to be homogenous by polyacrylamide gel electrophoresis. The purified enzyme displayed two protein bands on SDS-polyacrylamide gel electrophoresis and its molecular mass was estimated to 80-87 kDa. The xylanase exhibited maximum activity at 65-70°C and at pH 5.6, but it retained more than 80% of its activity in the pH range 5.0-6.0. The enzyme was stable for a long time-period up to 50°C and for 1 h at 60°C. Although the xylanase had a lower carboxymethylcellulase activity, it lacked activity towards substituted xylan, xylobiose, inulin, starch, polygalacturonic acid or pNP-glycosides. Kinetic parameters indicated higher efficiency in the hydrolysis of beechwood xylan and birchwood xylan. The xylanase activity was stimulated by K⁺, Mn²⁺ and dithiol-reducing agents and was sensitive to Cu²⁺, Fe²⁺, Zn²⁺ and detergent agents. The enzymatic activity was observed in presence of urea up to a 1% (w/v) concentration. The enzyme could also be used in the presence of organic solvents such as acetone or dioxane (5%, v/v) without loss of activity.

Key words: Xylanase, Thermostable Termitomyces sp., Macrotermes subhyalinus, Termitidae.