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Clostridium botulinum
Clostridium botulinum stained with gentian violet.
Scientific classification
Domain: Bacteria
Division: Firmicutes
Class: Clostridia
Order: Clostridiales
Family: Clostridiaceae
Genus: Clostridium
Species: C. botulinum
Binomial name
Clostridium botulinum
van Ermengem, 1896

Clostridium botulinum is a Gram-positive, rod shaped bacterium that produces the neurotoxin botulin, which causes flaccid muscular paralysis seen in botulism, and is also the main paralytic agent in botox. It is an anaerobic spore-former, which produces oval, subterminal endospores and is commonly found in soil.



Clostridium botulinumis a rod-shaped microorganism. It is an obligate anaerobe, meaning that oxygen is poisonous to the cells. However, they tolerate very small traces of oxygen due to the enzyme called superoxide dismutase (SOD) which is an important antioxidant defense in nearly all cells exposed to oxygen. [1] Clostridium botulinum does not form endospores as a way to protect the viability of the organism, but rather as a mechanism to produce the neurotoxin. Clostridium botulinum is only able to produce the neurotoxin during the process of producing the endospore and this can only happen in an anaerobic environment. Unlike other microbiological organisms which produce spores in an unfavorable growth environment to preserve the organism's viability and allows them to survive in a dormant state until such time the spores are exposed to conditions that can support their growth. An example of how botulisum could occur, would be as a result of improperly preserved or home canned low acid vegetables that were not processed using correct preservation times and or pressure. As an added precaution, Clostridium botulinum endospore production enables the organism to produce the potent neurotoxin, and therefore all home-canned vegetables and meats should be boiled without tasting for 10 minutes plus one minute per 1,000 feet above sea level (15 minutes at 5,000 feet). Boil home-canned spinach and corn 20 minutes before tasting. If the food looks spoiled, foams or has an off odor during heating, do not eat, discard and decontaminate any surfaces the food may have touched.

In the laboratory Clostridium botulinum is usually isolated in tryptose sulfite cycloserine (TSC) growth media, always in an anaerobic environment with less than 2% of oxygen. This can be achieved by several commercial kits that use a chemical reaction to replace O2 with CO2 (E.J. GasPak System). C. botulinum is lipase negative microorganism, it grows between pH values of 4.8 and 7 and it can't use lactose as a primary carbon source, characteristics important during a biochemical identification.[2]

Taxonomy history

Clostridium botulinum was first recognized and isolated in 1896 by Emile van Ermengem from home cured ham implicated in a botulism outbreak.[3] The isolate was originally named Bacillus botulinus. However, isolates from subsequent outbreaks were always found to be anaerobic spore formers, so Bengston proposed that the organism be placed into the genus Clostridium as the Bacillus genus was restricted to aerobic spore-forming rods.[4]

Since 1953 all species producing the botulinum neurotoxins (types A-G) have been designated C. botulinum. Substantial phenotypic and genotypic evidence exists to demonstrate heterogeneity within the species. This has led to the reclassification of C. botulinum type G strains as a new species Clostridium argentinense.[5]

Clostridium botulinum strains that do not produce a botulin toxin are referred to as Clostridium sporogenes.[6]

The complete genome of C. botulinum has been sequenced Sanger.


The current nomenclature for C. botulinum recognises four physiological groups (I-IV). This is mostly based on the ability of the organism to digest complex proteins.[7][8] Studies at the DNA and rRNA level support the subdivision of the species into groups I-IV. Most outbreaks of human botulism are caused by group I (proteolytic) or II (non-proteolytic) C. botulinum. Group III organisms mainly cause diseases in animals. There has been no record of Group IV C. botulinum causing human or animal disease.

Neurotoxin types

Neurotoxin production is the unifying feature of the species C. botulinum. Seven types of toxins have been identified and allocated a letter (A-G). Most strains produce one type of neurotoxin but strains producing multiple toxins has been described. Clostridium botulinum producing B and F toxin types have been isolated from human botulism cases in New Mexico and California.[9] The toxin type has been designated Bf as the type B toxin was found in excess to the type F. Similarly, strains producing Ab and Af toxins have been reported. There is evidence that the neurotoxin genes have been the subject of horizontal transfer, possibly from a viral source. This theory is supported by the presence of integration sites flanking the toxin in some strains of C. botulinum. However, these integrations sites are degraded indicating that the C. botulinum acquired the toxin genes quite far into the evolutionary past.

Only types A, B, E, and F cause disease in humans while types C and D cause disease in cows, birds, and other animals but not in humans. The "gold standard" for determining toxin type is a mouse bioassay, but the genes for types A, B, E, and F can now be readily differentiated using real-time PCR.[10]

Organisms genetically as they identified as other Clostridium species have caused human botulism; Clostridium butyricum producing type E toxin[11] and Clostridium baratii producing type F toxin.[12][13] The ability of C. botulinum to naturally transfer neurotoxin genes to other clostridia is concerning, especially in the food industry where preservation systems are designed to destroy or inhibit only C. botulinum but not other Clostridium species.

Phenotypic groups of Clostridium botulinum
Properties Group I Group II Group III Group IV
Toxin Types A, B, F B, E, F C, D G
Proteolysis + - weak -
Saccharolysis - + - -
Disease host human human animal -
Toxin gene chromosome chromosome bacteriophage plasmid
Close relatives C. sporogenes, C. putrificum C. butyricum, C. beijerinickii C. haemolyticum, C. novyi type A C. subterminale, C. haemolyticum

Clostridium botulinum in different geographical locations

A number of quantitative surveys for C. botulinum spores in the environment have suggested a prevalence of specific toxin types in given geographic areas, which remain unexplained.


North America

Type A C. botulinum predominates the soil samples from the western regions while type B is the major type found in eastern areas.[14] The type B organisms were of the proteolytic type I. Sediments from the Great Lake regions were surveyed after outbreaks of botulism among commercially reared fish and only type E spores were detected.[15][16][17] It has been noted in a survey that type A strains were isolated from soils that were neutral to alkaline (average pH 7.5) while type B strains were isolated from slightly acidic soils (average pH 6.25).


Clostridium botulinum type E is prevalent in aquatic sediments in Norway and Sweden,[18] Denmark,[19] the Netherlands, the Baltic coast of Poland and Russia.[14] It was then suggested that the type E C. botulinum is a true aquatic organism and this was shown by the correlation between the level of type E contamination and flooding of the land with seawater. As the land dried, the level of type E decreased and type B became dominant.

In soil and sediment from the United Kingdom, C. botulinum type B predominates. In general, the incidence is usually lower in soil than in sediment. In Italy, a survey was conducted in the vicinity of Rome, and a low level of contamination was found; all strains were proteolytic C. botulinum type A or B.[20]


Clostridium botulinum type A was found to be present in soil samples from mountain areas of Victoria.[21] Type B organisms were detected in marine mud from Tasmania.[22] Type A C. botulinum have been found in Sydney suburbs and types A and B were isolated from urban areas. In a well defined area of the Darling-Downs region of Queensland, a study showed the prevalence and persistence of C. botulinum type B after many cases of botulism in horses.


A "mouse protection" or "mouse bioassay" test determines the type of C. botulinum present using monoclonal antibodies. This can now also be accomplished using real-time PCR.[23]

Clostridium botulinum is also used to prepare the medicaments Botox, Dysport, Xeomin, and Neurobloc used to selectively paralyze muscles to temporarily relieve muscle function. It has other "off-label" medical purposes, such as treating severe facial pain, such as that caused by trigeminal neuralgia.

Botulin toxin produced by Clostridium botulinum is often believed to be a potential bioweapon as it is so potent that it takes about 75 nanograms to kill a person (LD50 of 1ng/kg,[24] assuming an average person weighs ~75kg); 500 grams of it would be enough to kill half of the entire human population.

Clostridium botulinum is a soil bacterium. The spores can survive in most environments and are very hard to kill. They can survive the temperature of boiling water at sea level, thus many foods are canned with a pressurized boil that achieves an even higher temperature, sufficient to kill the spores.

Growth of the bacterium can be prevented by high acidity, high ratio of dissolved sugar, high levels of oxygen, very low levels of moisture or storage at temperatures below 38°F (type A). For example in a low acid, canned vegetable such as green beans that are not heated hot enough to kill the spores (i.e., a pressurized environment) may provide an oxygen free medium for the spores to grow and produce the toxin. On the other hand, pickles are sufficiently acidic to prevent growth; even if the spores are present, they pose no danger to the consumer. Honey, corn syrup, and other sweeteners may contain spores but the spores cannot grow in a highly concentrated sugar solution; however, when a sweetener is diluted in the low oxygen, low acid digestive system of an infant, the spores can grow and produce toxin. As soon as infants begin eating solid food, the digestive juices become too acidic for the bacterium to grow.

External links


  1. ^ Doyle, Michael P. (2007). Food Microbiology: Fundamentals and Frontiers. ASM Press. 
  2. ^ . (2005). Brock Biology of Microorganisms (11th ed.). Prentice Hall. ISBN 0131443291. 
  3. ^ E. van Ergmengem. 1897. Über einen neuen anaeroben Bacillus und seine Beziehungen Zum Botulismus. Zentralbl. Hyg. Infektionskr. 26:1–8.
  4. ^ I. A. Bengston. 1924. Studies on organisms concerned as causative factors in botulism. Hyg. Lab. Bull. 136:101
  5. ^ J. C. Suen, C. L. Hatheway, A. G. Steigerwalt, D. J. Brenner. 1988, Clostridium argentinense sp.nov.: a genetically homogeneous group composed of all strains of Clostridium botulinum type G and some nontoxigenic strains previously identified as Clostridium subterminale or Clostridium hastiforme. Int. J. Sys. Bacteriol. 38:375–381.
  6. ^ Judicial Commission of the International Committee on Systematic Bacteriology (1999) Rejection of Clostridium putrificum and conservation of Clostridium botulinum and Clostridium sporogenes Opinion 69. International Journal of Systematic Bacteriology. 49:339.
  7. ^ L. V. Holdeman, J. B. Brooks. 1970. Variation among strains of Clostridium botulinum and related clostridia. Protocols of the first U.S-Japan conference on Toxic Microorganisms. pp. 278–286
  8. ^ L. D. S. Smith, G. Hobbs. 1974. Genus III Clostridium Prazmowski 1880, 23. In R. E. Buchanan, N. E. gibbons (eds.), Bergey’s Manual of Determinative Bacteriology, 8th edition. William & Wilkins, Baltimore. pp. 551–572.
  9. ^ C. L. Hatheway, L. M. McCroskey. 1987. Examination of faeces for diagnosis of infant botulism in 336 patients. J. Clin. Microbiol. 25:2334–2338.
  10. ^ Satterfield, B. A., Stewart, A. F., Lew, C. S., Pickett, D. O., Cohen, M. N., Moore, E. A., Luedtke, P. F., O’Neill, K. L. & Robison, R. A. (2010). A quadruplex real-time PCR assay for rapid detection and differentiation of the Clostridium botulinum toxin genes A, B, E and F. J Med Microbiol 59, 55-64.
  11. ^ P. Aureli, L. Fenicia, B. Pasolini, M. Gianfrancesche, J. M. Mccroskey, C. L. Hatheway. 1986. Two cases of type E infant botulism caused by neurotoxigenic Clostridium botulinum in Italy. J. Infect. Dis. 154:207–211.
  12. ^ J. D. Hall, L. M. McCroskey, B. J. Pincomb, C. L. Hatheway. 1985. Isolation of an organism resembling Clostridium baratii which produces a type F botulinal toxin from an infant with botulism. J. Clin. Microbiol. 21:654–655.
  13. ^ S. Notermans, A. H. Havellar. 1980. Removal and inactivation of botulinum toxin during production of drinking water from surface water. Antonie van Leeuwenhoek 46:511–514.
  14. ^ a b A. H. W. Hauschild. 1989. Clostridium botulinum. In M. P. Doyle (ed.), Food-borne Bacterial Pathogens. Marcel Dekker, New York. Pp. 111–189
  15. ^ T. L. Bott, J. Johnson, E. M. Foster, H. Sugiyama. 1968. Possible origin of the fish incidences of Clostridium botulinum type E in an inland bay (Green Bay of Lake Michigan). J. Bacteriol. 95:1542.
  16. ^ M. W. Eklund, M. E. Peterson, F. T. Poysky, L. W. Peck, J. F. Conrad. 1982. Botulism in juvenile Coho salmon (Onocorhynchus kisutch) in the United States. Aquaculture 27:1–11
  17. ^ M. W. Eklund, F. T. Poysky M. E. Peterson, L. W. Peck, Brunson. 1984. Type E botulism in salmonids and conditions contributing to outbreaks. Aquaculture 41:293–309.
  18. ^ A. Johannsen. 1963. Clostridium botulinum in Sweden and the adjacent waters. J. Appl. Bacteriol. 26:43–47.
  19. ^ H. H. Huss 1980. Distribution of Clostridium botulinum. Appl. Environ. Microbiol. 39:764–769.
  20. ^ R. Creti, J. Fenicia, P. Aureli. 1990. Occurrence of Clostridium botulinum in the soil of the vicinity of Rome. Curr. Microbiol. 20:317.
  21. ^ C. E. Eales, J. M. Gillespie. 1947. the isolation of Clostridium botulinum type A from Victorian soils. Aust. J. Sci. 10:20–21.
  22. ^ D. f. Ohye, W. J. Scott. 1957. Studies in the physiology of Clostridium botulinum type E. Aust. L. Biol. Sci. 10:85–94.
  23. ^ Satterfield, B. A., Stewart, A. F., Lew, C. S., Pickett, D. O., Cohen, M. N., Moore, E. A., Luedtke, P. F., O’Neill, K. L. & Robison, R. A. (2010). A quadruplex real-time PCR assay for rapid detection and differentiation of the Clostridium botulinum toxin genes A, B, E and F. J Med Microbiol 59, 55-64.
  24. ^ By Diane O. Fleming, Debra Long Hunt. Biological Safety: principles and practices. ASM Press, 2000, p. 267.


Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary


Proper noun

Clostridium botulinum

  1. (taxonomy) A taxonomic species within the genus Clostridium — the bacterium that secretes the toxin botulin.


Up to date as of January 23, 2010

From Wikispecies


Main Page
Superregnum: Bacteria
Regnum: Bacteria
Phylum: Firmicutes
Classis: Clostridia
Ordo: Clostridiales
Familia: Clostridiaceae
Genus: Clostridium
Species: Clostridium botulinum
Subspecies: Clostridium botulinum A - Clostridium botulinum F -



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