Clostridium botulinum depicted below is a Gram-positive, anaerobic, rod-shaped, spore-forming bacterium that produces the most potent biological toxin known, botulinum neurotoxin. Botulinum toxins are neurotoxic and therefore affect the nervous system. Foodborne botulism is characterized by descending, flaccid paralysis that can cause respiratory failure.  

Botulism is usually associated with foods that have received insufficient or no preservation treatment, been kept out of the refrigerator for a while, and been eaten without the proper heating are typically linked to botulism. A bad smell that alerts consumers to the presence of Clostridium botulinum in food is often, but not always, produced by the bacteria.  

Since heat kills botulinum spores, under-sterilization; either by processing at a temperature too low or for an excessively short period of time, or a combination of these is the main offender in home canning. 

Prevention of foodborne botulism is based on good practice in food preparation particularly during heating/sterilization and hygiene.