Isolation of mutants of Penicillium purpurogenum resistant to catabolite repression

 The strain Penicillium purpurogenum P-26 was subjected to UV irradiation and N-methyl-N′-nitro-N-nitrosoguanidine treatment and mutants were isolated capable of synthesizing cellulase under the conditions of a high concentration of glucose. Initially mutants resistant to catabolite repression by 2-deoxy-D-glucose were isolated on Walseth’s cellulose/agar plates containing 15–45 mM 2-deoxy-D-glucose. These mutants were again screened for resistance to catabolite repression by glycerol or glucose on Walseth’s cellulose/agar plates containing 50 g/l glycerol or 50 g/l glucose respectively. Four mutants with different sizes of clearing zone on Walseth’s cellulose/agar plates containing 50 g/l glucose were selected for flask culture. Among them, the mutant NTUV-45-4 showed better carboxymethylcellulase activity in flask culture containing 1% Avicel plus 3% glucose than did the parental strain. Received: 9 October 1995/Received revision: 27 November 1995/Accepted: 8 January 1996