Induction of Cellulase by Gentiobiose and Its Sulfur-Containing Analog in Penicillium purpurogenum

Abstract

Cellulase induction by β-glucodisaccharides was investigated by using non-cellulase-induced mycelia of Penicillium purpurogenum P-26, a highly-cellulase-producing fungus. Gentiobiose induced significant amounts of cellulase compared with cellobiose when nojirimycin was added to the induction medium to inhibit extracellular β-glucosidase activity. Thiogentiobiose (6- S -β- d -glucopyranosyl-6-thio- d -glucose), a sulfur-containing analog of gentiobiose, was more effective for cellulase induction than gentiobiose even in the absence of nojirimycin. Thiogentiobiose appeared to be a gratuitous inducer since it was not metabolized during cellulase induction. Gentiobiose was formed from cellobiose by the intracellular β-glucosidase of P. purpurogenum. These findings indicate that gentiobiose is an active inducer of cellulase for this fungus and may possibly be formed by intracellular β-glucosidase from cellobiose.