5QO MICROBIOLOGY OF FOODS 



The poison of B. botulinus is a true bacterial toxin, which in its 

 potency belongs in a class with the toxin of diphtheria and tetanus. 

 Dickson has produced a crude toxin of which o.oooi c.c. killed a guinea- 

 pig within twenty-four hours. Unlike these other toxins, however, 

 botulin (the botulinus toxin) is actively poisonous when swallowed 

 with food as well as when injected into the tissues. An, antitoxic 

 serum has been produced by immunization of goats. This serum has 

 considerable value in preventing the disease but little value in treat- 

 ment after the symptoms have appeared. The analogy with tetanus 

 is evident. Botulin, like the tetanus toxin, has a strong avidity for 

 nerve tissue. The toxin loses strength slowly when heated at 56C. 

 and is rendered harmless by heating at 8oC. for thirty minutes or by 

 boiling for five minutes. 



Botulism has long been known as a form of meat poisoning and it 

 has also been known that vegetable foods of high protein content, such 

 as beans, might give rise to this poisoning. The clinical and experi- 

 mental observations of Dickson, Graham and his associates have called 

 attention to the possible production of botulinus toxin in various vege- 

 table foods, including canned corn, asparagus, spinach, apricots and 

 peaches as well as oats, hay and ensilage. The virulence of the poison 

 is such that a mere taste of the tainted food is sufficient to cause serious 

 illness and the swallowing of a single spoonful has caused fatal poisoning. 



Botulism may be caused, therefore, not only by the consumption 

 of meats and meat products but also of vegetable foods and it is especially 

 important at this time to emphasize the danger in canned foods, espe- 

 cially in home canned foods. So far, botulism has been traced to com- 

 mercial canned foods very rarely indeed but the methods used at 

 home, especially the cold-pack method, may be quite inadequate to 

 destroy spores of B. botulinus if they have gained access to the food. The 

 canning of vegetables which are not sound and clean is an important 

 source of danger. Even in commercial canning with standardized methods 

 and control it is doubtful whether the heating is adequate to destroy 

 spores of B. botulinus. Weinzirl* has found viable spores of aerobic 

 bacteria in marketable commercial canned foods and he regards the 

 absence of oxygen as essential to the preservation of such canned foods. 

 If the spores of B. botulinus are as resistant as appears from the studies 

 of Burke, then we must expect botulism from commercial canned foods 



* Weinzirl, J. The bacteriology of canned foods. Journal of Med. Rsch., Jan., 1919, 

 Vol. 39, No. 3, p. 348-413. 



