Clostridium botulinum is a Gram-positive bacterium of the Firmicutes. An important characteristic of this bacterium is its ability to form endospores in undesirable conditions. C. botulinum is also an obligate anaerobe; however, this bacterium can produce an enzyme called superoxide dismutase which can defend the bacterium from small traces of O2. The most distinguishable trait of C. botulinum is its ability to produce the neurotoxin botulin. This neurotoxin is very deadly and is associated with causing flaccid muscular paralysis seen in botulism and is the main paralytic ingredient in Botox.
Clostridium botulinum is a rod-shaped bacterium and can be grown in the laboratory. C. botulinum usually requires tryptose sulfite cycloserine (TSC) growth media and must always be incubated in an anaerobic environment with less than 2% of O2. This bacterium also requires a pH between 4.8 and 7. C. botulinum cannot metabolize lactose as a primary carbon source.
The spore forming C. botulinum is normally found in soil and aquatic sediments. The neurotoxin that this bacterium can produce is extremely lethal and must be treated immediately. There are several different types of botulism toxin classified by their antigenic specificity. The types A,B, E, and F cause human botulism and types C and D cause animal botulism. The disease mainly comes from inadequately processed foods which contain either the toxin or bacterium. A person could also contract botulism from a wound being contaminated with the toxin. If a gastrointestinal tract is compromised, C. botulinum could also grow there but this normally only happens in infants that haven’t yet developed acidic digestive juices.
The botulin toxin also has potential to be a bioweapon since it is extremely potent. The median lethal dose is 1 ng/kg which is 75 nanograms to kill an average person of 75 kg. The toxin is also non-proteolytic, which means that affected food may look and smell normal. The symptoms of this toxin include blurred vision, diplopia, weakness, and symmetric paralysis. A blood serum or stool sample should be sufficient in detecting the toxin.Clostridium botulinum is also used to make Botox, Dysport, Xeomin, and Neurobloc by selectively paralyzing muscles to temporarily reduce muscle function. C. botulinum can be used to treat severe facial pain caused by trigeminal neuralgia as well.
The spores of C. botulinum are extremely heat resistant which makes them difficult to kill by just boiling water. Many canned foods which could contain this bacterium are pressure boiled at a very high temperature that is sufficient in killing the spores. Some foods based on their acidic and sugar levels may contain spores yet they will not harm the consumer. For example, pickles are sufficiently acidic to stop the growth of the bacterium. Even honey and corn syrup may contain spores but they will not be able to grow in a strong sugar concentration. Infants however should avoid these foods until they have had time to build up acidic juices in their GI tract.
Much work is being done to better understand this bacterium. There have been recent reports of other Clostridium species causing human botulism; Clostridium butyricum producing type E toxin and Clostridium baratii producing type F toxin. There is a concerning fear that C. botulinum may have the ability to naturally transfer neurotoxin genes to other clostridium species. This could be very bad for the food industry where preservation systems are designed to destroy or inhibit only C. botulinum but not other Clostridium species.
The Insitute of Food Research in the U.K. are working to determine the molecular basis of the physiological responses of C. botulinum when subjected to food- and gut-relevant stresses. They want to determine the molecular mechanisms of physiological strategies used by C. botulinum to begin growth, and identify the transcriptional programming responsible for germination and neurotoxin production by this bacterium.
References
Bbb - clostridium botulinum. (2009, September 21). Retrieved from http://www.fda.gov/food/foodsafety/foodborneillness/foodborneillnessfoodbornepathogensnaturaltoxins/badbugbook/ucm070000.htm
Clostridium botulinum. (2099). Retrieved from http://www.ifr.ac.uk/info/science/FoodbornePathogens/Cbotulinum.htm
Pathema - clostridium. (1999). Bioinformatics Resource Center, Retrieved from http://pathema.jcvi.org/cgi-bin/Clostridium/PathemaHomePage.cgi
Todar, K. (2009). Pathogenic clostridia, including botulism and tetanus [Chapter 4]. Retrieved from http://textbookofbacteriology.net/clostridia.html
*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.
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