Properties of Cellulases of Two Brown-Rot Fungi and Two White-Rot Fungi

Terry L. Highley

Abstract


Cellulases from two brown-rot fungi (Cx) and from two white-rot fungi (Cx and C1) were compared. The Cx cellulases of the brown-rot and the white-rot fungi responded differently to pH and temperature effects. Cx activity of the brown-rot fungi was optimum in the low pH region—2 to 3, whereas the activity of the white-rot fungi was considerably lower than optimum. Cx activity of the white-rot fungi was more depressed at low temperatures than was that of the brown-rot fungi. Stability of Cx from the brown-rot fungi was uniform for the range 23 to 60 C, whereas Cx from the white-rot fungi was substantially reduced at temperatures above 50 C. The C1 cellulases produced by only the white-rot fungi were more unstable than those of the Cx to pH and temperature changes. Sulf-hydryl groups apparently are not active sites for any of the cellulases. Degradation of carboxymethylcellulose by Cx was similar for the four fungi and proceeded in a random manner; degradation of microerystalline cellulose by C1 was in an endwise manner, and evidently acts as a β-1-4-glucan cellobiohydrolase. β-glucosidase produced by the four fungi hydrolyzed the cellulase breakdown products to glucose.

Keywords


<i>Coriolus versicolor</i>;<i>Ganoderma applanatum</i>;<i>Poria monticola</i>;<i>Gloeo-phyllum trabeum</i>;cellulase;enzyme;wood decay;enzyme activity;enzyme stability

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