MadSci Network: Microbiology

Re: Can 'Clostridium Botulinum' (bacteria toxin) be made non-toxic by over-cook

Date: Fri Nov 5 10:24:38 1999
Posted By: Glynis Kolling, Grad student, Food Science, Rutgers Univeristy
Area of science: Microbiology
ID: 940609999.Mi

  These are all very good questions about C. botulinum and the botulinum 
neurotoxin (BoNT).  The BoNT is destroyed by high temperatures, cooking 
and/or boiling for 10 minutes is sufficient for toxin inactivation. The 
foods that are a particular concern for C. botulinum growth are home-canned 
foods; but, there are still instances where commercial canned foods are 
associated with botulism. 

   I don't believe that getting toxin into a wound would result in 
botulism.  The reason that I say this is because C. botulinum is an 
anaerobic bacterium; therefore, it is likely that toxin production takes 
place under anaerobic conditions - so the chances of the toxin existing in 
a place where there is an aerobic environment are pretty slim.  It is 
possible for "wound botulism" to exist; however, this usually occurs when a 
wound (most likely a deep wound where there is an anaerobic environment)is 
infected with C. botulinum.  Once C. bot is in the wound (in vivo), it 
will then produce BoNT.  As a general rule of bacterial toxins, it is 
likely that a bacteria will only produce toxins when conditions are 
favorable; i.e. they have a plethora of nutrients, optimal environmental 
conditions, etc.

   If the spores are inhaled (and stay as spores), I would guess that a 
perfectly healthy person, with a competent immune system would not develop 
signs of botulism because the body will mount an immune response and get 
rid of the spores.  Immunocomprimised persons (extremely young, elderly, 
AIDS, etc.) may be more susceptible to developing botulism; however, I 
don't know if there is any evidence specifically documenting this.

   As far as absorption of the toxin is concerned, I am not sure if it is 
absorbed into the stomach lining.  BoNT is a neurotoxin, so it acts at the 
neurons.  Specifically, it inhibits neurotransmitter release at the 
neuromuscular junction; resulting in a flaccid paralysis. Other 
(early) signs of botulism are nausea, diarrhea, visual disturbances, and 
dry mouth.  Later symptoms will include severe respiratory and motor 
impairment...which can lead to death.  

  I hope that I have satisfied your curosity about botulism; if you would 
like more information, I highly recommend visiting the Centers for Disease 
Control and Prevention - they are an excellent source! For information on 
botulism, go to: 
   There are a couple of links on that page which may give you more 
information on incidence, and other details.  Good luck!

    Glynis K. 
    Rutgers University, Food Science Dept.

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