Production of ethanol from biomasses. Part II. Preparation of mutants resistant to catabolite repression of Trichoderma reesei.

Abstract

The development of agar plate screening techniques has allowed the isolation of mutants of Trichoderma reesei capable of synthesizing cellulase under the conditions of a high concentration of glucose. Mutants resistant to catabolite repression by glycerol or glucose were isolated on Walseth's cellulose (WC)agar plates containing 5%glycerol or 5%glucose, respectively. Mutants resistant to catabolite repression by glycerol were not derepressed enough for the production of cellulase on WCagar plates containing 5% glucose or in flask cultures with a mixture of 1 % Avicel and 3%glucose. On the contrary, two mutant strains resistant to catabolite repression by glucose (KDD-10 and DGD-16) produced large clearing zones on WCagar plates containing 5% glucose. Both strains could begin to produce CMCaseeven in the presence of residual glucose and finally produced 1.5 times the CMCaseactivity, in flask cultures on 1%Avicel and 3%glucose, than that with 1%Avicel alone. These results suggest that KDD-10and DGD-16are comparatively derepressed by glucose for cellulase production.