[Regulation of the biosynthesis of endo-1,4-beta-glucanase, eco-1,4-beta-glucosidase and cellobiase in Aspergillus terreus].

This work was aimed at studying how the biosynthesis of endo-1,4-beta-glucanase, exo-1,4-beta-glucosidase and cellobiase, components of the cellulase complex was regulated in an Aspergillus terreus strain isolated from soil. The biosynthesis of endoglucanase and cellobiase was suppressed by readily metabolizable substrates and stimulated in the course of growth on lactose and celluloses. The activity of exoglucosidase was found in the medium only when the strain was grown on celluloses. Catabolite repression was assumed to be an important mechanism regulating the biosynthesis of cellulases by the culture. The derepression was insufficient however to stimulate the biosynthesis of all the three enzymes. Besides lactose and celluloses, cellobiose taken at a low concentration also exhibited the inducing effect. Under the conditions of derepression and induction, the activity of the three enzymes, the components of the complex, increases in the growth medium in parallel to the cultural growth. The synthesis and excretion of endoglucanase and exoglucosidase coincided in time whereas a considerable portion of the cellobiase activity was displayed by the cells. The results suggest that the regulation of endoglucanase, exoglucosidase and cellobiase biosynthesis are coordinated at the level of catabolite repression and induction.