SCREENING OF CATABOLITE REPRESSION-RESISTANT MUTANTS OF CELLULASE PRODUC1NG PENICILLIUM SPP
青霉的纤维素酶抗降解物阻遏突变株的选育

A screening method of double layer agar plate was improved by using holocellulose instead of acid-swollen cellulose as substrate. Using this method, a high cellulase producing fungus Penicillium decumbens 114-2 was isolated from the soil. The strain 114-2 was continually mutated with UV and NG. A series of catabolite- derepression mutants were selected on the holocellulose plate in the presence of excessive glucose. These mutants can hydrolyze holocellulose in the plate, but neither the parent strain 114-2 nor two of the high cellulase producing mutants (Trichoderma EA_3-867 and QM9414) have tais ability. Among the non-repressible cellulase producing mutants, two strains, JN15 and JU1, clearly produced a great amount of cellulase in the liquid holocel- lulose-glucose medium. In addition, when JU1 was grown on a medium containing holocellulose as the sole carbon source, the sasccharifying cellulase activities of JU1 on filter paper, CMC and cotton were as high as 33 mg glucose/ml. h, 234 mg glucose/ml.h and 86 mg glucose/ml.24h respectively. The cellulase production of P. decumbens strains, especially in JU1, is more sensi- tive to low pH. Thus, the addition of CaCO_3 is favorable.