Cholera toxin-like toxin released by Salmonella species in the presence of mitomycin C

Several serotypes of Salmonella were shown to release increased amounts of a cholera toxin-like toxin during culture in vitro with mitomycin C (MTC). Filter-sterilized culture supernatants containing the toxin caused elongation of Chinese hamster ovary cells, which could be blocked by heating the supernatants at 100°C for 15 min or by adding mixed gangliosides or monospecific cholera antitoxin. When MTC was not added to the Salmonella cultures, little or no toxin was detected in crude, unconcentrated culture supernatants. Optimal production of toxin was observed in the presence of 0.5 μg of MTC per ml in shake flask cultures of Casamino Acids-yeast extract medium, Syncase, or peptone saline at 37°C. Meat infusion media (heart infusion and brain heart infusion) plus MTC resulted in poor toxin yield. Culture filtrates frequently could be diluted 1:8 and still result in elongation of Chinese hamster ovary cells.