Cellulase and Xylanase Activities in Higher Basidiomycetes

V. I. Elisashvili^*, T. Sh. Khardziani, N. D. Tsiklauri, and E. T. Kachlishvili

Institute of Plant Biochemistry, Georgian Academy of Sciences, Agmashenebeli Alley 10 km, Tbilisi, 380059 Georgia; fax: (995-32) 00-1153; E-mail: velisashvili@hotmail.com

^* To whom correspondence should be addressed.

Received November 20, 1998; Revision received February 20, 1999

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Extracellular carboxymethylcellulase, xylanase, beta-glucosidase, and beta-xylosidase activities of four cultures of higher basidial fungi were studied in relation to the source of carbon in the nutrient medium. It was shown that beta-glucosidases and beta-xylosidases of all basidiomycetes and cellulases and xylanases of Pholiota aurivella IBR437 and Gloeophyllum saepiarium IBR155, the causal agents of wood brown rot, are constitutive enzymes; however, their activities depend on the source of carbon in the growth medium. Cellulases and xylanases of Coriolus pubescens IBR663 and Lentinus tigrinus IBR100 degrading wood through white rot are inducible enzymes. The synthesis of cellulases and xylanases was induced upon fungal growth on media containing crystalline cellulose and plant raw materials; carboxymethylcellulose and xylan were less effective. The induction of C. pubescens IBR663 cellulase and xylanase was observed when avicel was added to the culture growing on a mannitol-containing medium. Glucose at a concentration of 0.2-0.8% caused catabolite repression of C. pubescens IBR663 cellulase and xylanase. After utilization of glucose, leading to a decrease in its concentration below 0.1%, the synthesis of enzymes was resumed. These data indicate that the synthesis of cellulases and xylanases in the examined macromycetes is under common regulatory control.

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KEY WORDS: cellulases, xylanases, basidiomycetes, induction, catabolite repression

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