Which organism is the source of the botulinum toxin that can contaminate canned foods?

• A. Clostridium botulinum
• B. Bacillus cereus
• C. Listeria monocytogenes
• D. Staphylococcus aureus

Answer: (A)

Botulinum toxin in canned foods comes from Clostridium botulinum, a spore-forming anaerobe. In sealed, low-oxygen cans with low-acid foods, certain strains can germinate and produce this potent toxin, which causes serious illness. Proper canning uses high-pressure processing to destroy spores and prevent toxin formation; heat alone may not neutralize spores in these foods. The other organisms listed are linked to different foodborne illnesses—Bacillus cereus with emetic/diarrheal syndromes, Listeria monocytogenes with listeriosis, and Staphylococcus aureus with preformed enterotoxins—so they are not the source of the botulinum toxin in canned foods.