Isolation of a cured strain from Corynebacterium diphtheriae PW8

A nonlysogenic, non-toxinogenic strain was isolated from the PW8 strain of C. diphtheriae by two-step ultraviolet induction. This strain was lysed by phages derived from the PW8 strain but not by beta phages from the C7(beta) strain. When this cured strain was lysogenized with phages from the PW8 strain, toxin production by the resulting lysogens was about a half or a quarter of that of the parent strain PW8.