CONTROL OF β-GLUCOSIDASES IN SCHIZOPHYLLUM COMMUNE

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Abstract
Intra- and extra-cellular enzymes of Schizophyllum commune which hydrolyze various β-glucosidic linkages were investigated. Low specific activities of enzymes hydrolyzing p-nitrophenyl-β-D-glucoside (PNPG) were always present. Confrontation of mycelium with cellobiose and certain other β-linked compounds for 18 h induced an extracellular PNPGase while intracellular PNPGase increased 10-fold. Glucose repressed PNPGase formation in vivo and also competitively inhibited substrate hydrolysis in vitro. Various stages in the life cycle of S. commune were examined for induction by cellobiose and repression by glucose. Both phenomena were demonstrable throughout development, but basidiospore germlings were most responsive to β-glucosidase induction. Induction appeared dependent on protein synthesis and respiration, since specific metabolic inhibitors prevented the process. Fractionation of cellobiose-induced mycelium extracts showed multiple components hydrolyzing PNPG. The major fraction also hydrolyzed cellobiose and laminarin. Purification of cellobiose-culture filtrates showed only one enzyme component and this was directly comparable to the major intracellular fraction. One of the minor intracellular components hydrolyzed laminarin and the second pustulan.

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