Genetic Factors in Corynebacterium Diphtheriae Conversion1

The conversion to toxigenicity of nontoxigenic Corynebacterium diphtheriae strain C4 requires the active and continued participation of a specific bacteriophage (Groman, 1953, 1955). The facts supporting this statement are: (1) lysogenization with 3 phage results in a simultaneous change to toxigenicity, and (2) reversion of toxngemnc cells to the nonlysogenic state results in a return to the nontoxigenic state. The phage specificity in the conversion phenomenon is demonstrated by the isolation of a phage designated y, capable of lysogenizing C4 without converting it to toxigenicity. In the present work the serological relationship of ,B and y phage is described, as well as their interactions with host strain C4. Apparent recombination between , and y phage is reported in which the ability of , phage to convert to toxigenicity acts as a discrete genetic attribute of the phage.