Isolation catabolite repression mutants

Beckwith and his colleagues isolated a large family of mutants that were permanently catabolite-repressed. These mutants fell into two categories Those that could be pheno-typically corrected by growing in the presence of cAMP and those that could not. The first class of mutants were believed to be defective in the synthesis of cAMP, and the latter class were presumed to be defective in the protein receptor for cAMP. Cell-free extracts were prepared from... 

Isolation of Constitutive> Catabolite Repression, and End-Product Inhibition-Resistant Mutants... 

A number of selective-screening methodologies have been devised that have allowed isolation of a series of hyperproducing and catabolite repression-resistant mutants of T. reesei. Yields of cellulase of 15 units/ mL under controlled fermentor conditions have been achieved with both Rut-NG14 and Rut-C30. Quantitative reaction of Rut-NG14 enzyme preparation with purified antibodies to cellobiohydrolase shows that in this mutant, the cellobiohydrolase is specifically hyperproduced relative to the rest of the enzymes in the cellulase complex. Rut-C30, which was derived from Rut-NG14, shows resistance to catabolite repression for... 

The development of an agar plate screening technique has allowed the isolation of a range of mutants of Trichoderma reesei capable of biosynthesizing cellulase under conditions of high catabolite repression. Commercial aspects of the production and isolation of hyper-cellulase-producing mutants of T. reesei were discussed. 

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