Deoxyribonuclease Activity

The relationship of catalase, cystinase, and deoxyribonuclease activity to toxinogeny in Corynebacterium diphtheriae was examined. Mutants deficient in each activity were isolated after mutagenization of strain C4 with nitrosoguanidine. All mutants were converted to toxinogeny after lysogenization with beta-converting phage, thus establishing that there is no absolute link between toxin production and these enzymatic activities. No differences were observed in the rate of lysogenization of the mutants by beta-converting phage over that of the parental strain. However, the data suggest that catalase mutants lysogenic for beta phage are generally induced at a higher rate than the parental strain after irradiation with ultraviolet light. Cystinase mutants vary widely in their rate of induction whereas the deoxyribonuclease mutants are similar to the parental strain. The relationship of these results to the production of toxinogenic strains is discussed.