Cellulase biosynthesis during degradation of cellulose derivatives by Thermomonospora curvata

Abstract

A variety of commercially used cellulose derivatives were compared with crystalline cellulose as substrates for induction of cellulase biosynthesis in the actinomycete Thermomonospora curvata. Cellulase induction during growth on uncoated cellophane was as rapid as that on crystalline cellulose, but on coated cellophanes, induction was delayed. Susceptibility to enzymatic attack determined the inductive potential of the substrate. Cellulose acetate was a poor substrate because of its extreme recalcitrance to attack. With other cellulose derivatives, soluble sugar accumulation caused a transient repression of cellulase biosynthesis, but the ratio of cellobiose (a cellulase inducer) to glucose (a cellulase repressor) was not a controlling factor. Crystalline cellulose yielded the lowest inducer/repressor sugar ratio (1.1:1 compared to 3.8–4.0:1 for cellulose derivatives), but supported the highest cellulase production. Glucose could not repress cellulase biosynthesis in the presence of cellobiose due to the strong preference for uptake of the disaccharide even by glucose‐grown cells.