In the late 1700s, Germany experienced several outbreaks of an illness connected to eating specific sausages. In 1817, the German neurologistJustinus Kerner detected rod-shaped cells in his investigations into this so-called sausage poisoning. In 1897, the Belgian biology professorEmile van Ermengem published his finding of an endospore-forming organism he isolated from spoiled ham. Biologists classified van Ermengem's discovery along with other known gram-positive spore formers in the genusBacillus. This classification presented problems, however, because the isolate grew only in anaerobic conditions, butBacillus grew well in oxygen.[1]
Circa 1880, in the course of studyingfermentation andbutyric acid synthesis, a scientist surnamed Prazmowski first assigned a binomial name toClostridium butyricum.[3] The mechanisms ofanaerobic respiration were still not yet well elucidated at that time, so taxonomy of anaerobes was still developing.[3]
In 1924,Ida A. Bengtson separated van Ermengem's microorganisms from theBacillus group and assigned them to the genusClostridium. By Bengtson's classification scheme,Clostridium contained all of the anaerobic endospore-forming rod-shaped bacteria, except the genusDesulfotomaculum.[1]
As of October 2022, there are 164 validly published species inClostridium.[4]
The genus, as traditionally defined, contains many organisms not closely related to itstype species. The issue was originally illustrated in full detail by arRNA phylogeny from Collins 1994, which split the traditional genus (now corresponding to a large slice ofClostridia) into twenty clusters, with clusterI containing the type speciesClostridium butyricum and its close relatives.[5] Over the years, this has resulted in many new genera being split out, with the ultimate goal of constrainingClostridium to clusterI.[6]
"Clostridium" clusterXIVa (nowLachnospiraceae)[7] and "Clostridium" clusterIV (nowRuminococcaceae)[7] efficiently ferment plant polysaccharide composing dietary fiber,[8] making them important and abundant taxa in therumen and the human large intestine.[9] As mentioned before, these clusters are not part of currentClostridium,[5][10] and use of these terms should be avoided due to ambiguous or inconsistent usage.[7]
Species ofClostridium areobligate anaerobe and capable of producingendospores. They generally staingram-positive, but as well asBacillus, are often described as Gram-variable, because they show an increasing number of gram-negative cells as the culture ages.[11]The normal, reproducing cells ofClostridium, called the vegetative form, arerod-shaped, which gives them their name, from theGreek κλωστήρ or spindle.Clostridium endospores have a distinct bowling pin or bottle shape, distinguishing them from other bacterial endospores, which are usually ovoid in shape.[citation needed] TheSchaeffer–Fulton stain (0.5%malachite green in water) can be used to distinguish endospores ofBacillus andClostridium from other microorganisms.[12]
There is a commercially availablepolymerase chain reaction (PCR) test kit (Bactotype) for the detection ofC. perfringens and other pathogenic bacteria.[13]
Clostridium species are readily found inhabiting soils and intestinal tracts.Clostridium species are also a normalinhabitant of the healthy lower reproductive tract of females.[14]
The main species responsible fordisease in humans are:[15]
The vegetative cells of clostridia are heat-labile and are killed by short heating at temperatures above 72–75 °C (162–167 °F). The thermal destruction ofClostridium spores requires higher temperatures (above 121.1 °C (250.0 °F), for example in anautoclave) and longer cooking times (20 min, with a few exceptional cases of more than 50 min recorded in the literature).Clostridia andBacilli are quite radiation-resistant, requiring doses of about 30 kGy, which is a serious obstacle to the development of shelf-stableirradiated foods for general use in the retail market.[22] The addition oflysozyme,nitrate,nitrite andpropionic acid salts inhibits clostridia in various foods.[23][24][25]
Clostridium botulinum produces a potentially lethalneurotoxin used in a diluted form in the drugBotox, which is carefully injected to nerves in the face, which prevents the movement of the expressive muscles of the forehead, to delay the wrinkling effect of aging. It is also used to treatspasmodic torticollis and provides relief for around 12 to 16 weeks.[28]
Clostridium butyricum strain MIYAIRI 588 is marketed in Japan, Korea, and China forClostridium difficile prophylaxis due to its reported ability to interfere with the growth of the latter.[29]
Nonpathogenic strains ofClostridium may help in the treatment of diseases such ascancer. Research shows thatClostridium can selectively target cancer cells. Some strains can enter and replicate within solidtumors.Clostridium could, therefore, be used to deliver therapeutic proteins to tumours. This use ofClostridium has been demonstrated in a variety of preclinical models.[35]
^GB application 191504845, Weizmann C, "Improvements in the Bacterial Fermentation of Carbohydrates and in Bacterial Cultures for the same", published 1919-03-06, assigned to Charles Weizmann andU.S. patent 1,315,585
^Hall, J; Ali, S; Surani, MA; Hazlewood, GP; Clark, AJ; Simons, JP; Hirst, BH; Gilbert, HJ (March 1993). "Manipulation of the repertoire of digestive enzymes secreted into the gastrointestinal tract of transgenic mice".Bio/technology (Nature Publishing Company).11 (3):376–9.doi:10.1038/nbt0393-376.PMID7763439.
^Zhang, JX; Meidinger, R; Forsberg, CW; Krell, PJ; Phillips, JP (15 July 1999). "Expression and processing of a bacterial endoglucanase in transgenic mice".Archives of biochemistry and biophysics.367 (2):317–21.doi:10.1006/abbi.1999.1243.PMID10395750.
