Clostridium botulinum is another organism that can survive pro-longed boiling and can multiply in the anaerobic environment provided by food that has been treated in this way. Unlike Clostridium welchii it is not found in the intestines of animals but is a soil saprophyte in many parts of the world, notably in the U.S.A. and may contaminate vegetable foods as well as fish and meat.
Home-preserved vegetables, particularly beans, have figured in a number of incidents; careful supervision of commercial canning of such items ensures that they are raised to temperatures that are lethal to clostridia.
It is far less common than the other forms of food-poisoning. It is due entirely to the exotoxin, the organisms themselves being harmless; and can be prevented by quite gentle cooking immediately before the food is eaten, as the toxin is destroyed in to minutes at too C.