THE EFFECT OF TEMPERATURE ON TOXIN FORMATION AND TOXIN STABILITY OF CLOSTRIDIUM BOTULINUM TYPE E IN DIFFERENT ENVIRONMENTS

Clostridium botulinum type E was found to produce toxin at temperatures between 3° and 30 °C in Robertson"s chopped meat medium and in fish dialyzate. Toxin was produced more rapidly in the meat medium. No toxin was found after 1 year of incubation at 1 °C. At 3 °C a slight toxin production was noticed after 120 days, when the inoculum consisted of a mixture of vegetative cells and spores.The lowest concentration of NaCl necessary to inhibit toxin production was found to vary with the incubation temperature and duration of storage. The inhibiting effect of NaCl was more pronounced at lower temperature.Type E spores mixed in fish meat medium heated for 110 min at 80 °C or for 10 min at 90 °C produced toxin during prolonged storage at 20 °C but not after they were heated at 90 °C for 20 min.Toxin (type E) proved more thermostable in meat broth and fish dialyzate than in phosphate buffer solution or in buffer supplemented with gelatine. In meat broth the toxin was inactivated after 5 min at 65 °C.