African Journal of Biotechnology Vol. 1 (2), pp. 64–66, December 2002

ISSN 1684-5315  © 2002 Academic Journals  

Influence of carbon source on the expression of Cochliobolus carbonum xylan-degrading enzyme genes

Nyerhovwo J. Tonukari^Y, *, John S. Scott-Craig and Jonathan D. Walton

Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824.

^Y Present address: International Livestock Research Institute, P.O. Box 30709, Nairobi, Kenya.

*Corresponding author; tel: 254-2-630743, fax: 254-2-631499, e-mail: J.TONUKARI@CGIAR.ORG

Accepted 18 November 2002

The expression of four Cochliobolus carbonum endo-1,4-b-xylanase genes (XYL1, XYL2, XYL3, XYL4), and an exo-1,4-b-xylosidase gene (XYP1) was studied following the growth of the fungus in minimal medium containing glucose, sucrose, xylose, xylan, pectin, or cellulose. The XYL1 and XYL2 genes were expressed only when the culture medium contained xylan or cellulose. Both XYL3 and XYL4 are induced by xylose and xylan, and XYP1 expression is induced by xylose, xylan, pectin and cellulose. None of these genes is expressed in glucose or sucrose media. The differential expression of these enzymes may provide means for the fungus to adapt to different conditions.

Key words: Cell wall degrading enzymes, Cochliobolus carbonum, xylan, xylanase.