Mitomycin-induced synthesis of a Shiga-like toxin from enteropathogenic Escherichia coli H.I.8.

Escherichia coli H.I.8, an O128 infant diarrhea isolate, produces low titers of a unique Shiga-like toxin (SLT), called SLT-IIva, which is a variant of SLT-II. We investigated induction of toxin synthesis and the putative association of a bacteriophage with toxin synthesis. Induction of broth cultures of strain H.I.8 with mitomycin yielded a 3,000-fold increase in SLT-IIva, production of a colicin, and appearance of a bacteriophage. Southern hybridization demonstrated that the genes for SLT-IIva were not carried by the bacteriophage.