Clostridium | |
---|---|
Photomicrograph of Clostridium botulinum bacteria stained with crystal violet | |
Scientific classification | |
Domain: | Bacteria |
Phylum: | Bacillota |
Class: | Clostridia |
Order: | Eubacteriales |
Family: | Lachnospiraceae |
Genus: | Clostridium Prazmowski 1880 |
Species | |
164 Species Contents |
Clostridium is a genus of anaerobic, Gram-positive bacteria. Species of Clostridium inhabit soils and the intestinal tract of animals, including humans. [1] This genus includes several significant human pathogens, including the causative agents of botulism and tetanus. It also formerly included an important cause of diarrhea, Clostridioides difficile , which was reclassified into the Clostridioides genus in 2016. [2]
In the late 1700s, Germany experienced several outbreaks of an illness connected to eating specific sausages. In 1817, the German neurologist Justinus Kerner detected rod-shaped cells in his investigations into this so-called sausage poisoning. In 1897, the Belgian biology professor Emile 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 genus Bacillus . This classification presented problems, however, because the isolate grew only in anaerobic conditions, but Bacillus grew well in oxygen. [1]
Circa 1880, in the course of studying fermentation and butyric acid synthesis, a scientist surnamed Prazmowski first assigned a binomial name to Clostridium butyricum. [3] The mechanisms of anaerobic 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 the Bacillus group and assigned them to the genus Clostridium. By Bengtson's classification scheme, Clostridium contained all of the anaerobic endospore-forming rod-shaped bacteria, except the genus Desulfotomaculum . [1]
As of October 2022, there are 164 validly published species in Clostridium. [4]
The genus, as traditionally defined, contains many organisms not closely related to its type species. The issue was originally illustrated in full detail by a rRNA phylogeny from Collins 1994, which split the traditional genus (now corresponding to a large slice of Clostridia) into twenty clusters, with cluster I containing the type species and its close relatives. [5] Over the years, this has resulted in many new genera being split out, with the ultimate goal of constraining Clostridium to cluster I. [6]
"Clostridium" cluster XIVa (now Lachnospiraceae) [7] and "Clostridium" cluster IV (now Ruminococcaceae) [7] efficiently ferment plant polysaccharide composing dietary fiber, [8] making them important and abundant taxa in the rumen and the human large intestine. [9] As mentioned before, these clusters are not part of current Clostridium, [5] [10] and use of these terms should be avoided due to ambiguous or inconsistent usage. [7]
Species of Clostridium are obligate anaerobe and capable of producing endospores. They generally stain gram-positive, but as well as Bacillus , 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 of Clostridium, called the vegetative form, are rod-shaped, which gives them their name, from the Greek 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 ] The Schaeffer–Fulton stain (0.5% malachite green in water) can be used to distinguish endospores of Bacillus and Clostridium from other microorganisms. [12]
Clostridium can be differentiated from the also endospore forming genus Bacillus by its obligate anaerobic growth, the shape of endospores and the lack of catalase. Species of Desulfotomaculum form similar endospores and can be distinguished by their requirement for sulfur. [1] Glycolysis and fermentation of pyruvic acid by Clostridia yield the end products butyric acid, butanol, acetone, isopropanol, and carbon dioxide. [11]
There is a commercially available polymerase chain reaction (PCR) test kit (Bactotype) for the detection of C. perfringens and other pathogenic bacteria. [13]
Clostridium species are readily found inhabiting soils and intestinal tracts. Clostridium species are also a normal inhabitant of the healthy lower reproductive tract of females. [14]
The main species responsible for disease in humans are: [15]
In general, the treatment of clostridial infection is high-dose penicillin G, to which the organism has remained susceptible. [19] Clostridium welchii and Clostridium tetani respond to sulfonamides. [20] Clostridia are also susceptible to tetracyclines, carbapenems (imipenem), metronidazole, vancomycin, and chloramphenicol. [21]
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 of Clostridium spores requires higher temperatures (above 121.1 °C (250.0 °F), for example in an autoclave) and longer cooking times (20 min, with a few exceptional cases of more than 50 min recorded in the literature). Clostridia and Bacilli are quite radiation-resistant, requiring doses of about 30 kGy, which is a serious obstacle to the development of shelf-stable irradiated foods for general use in the retail market. [22] The addition of lysozyme, nitrate, nitrite and propionic acid salts inhibits clostridia in various foods. [23] [24] [25]
Fructooligosaccharides (fructans) such as inulin, occurring in relatively large amounts in a number of foods such as chicory, garlic, onion, leek, artichoke, and asparagus, have a prebiotic or bifidogenic effect, selectively promoting the growth and metabolism of beneficial bacteria in the colon, such as Bifidobacteria and Lactobacilli, while inhibiting harmful ones, such as clostridia, fusobacteria, and Bacteroides . [26]
Clostridium botulinum is a gram-positive, rod-shaped, anaerobic, spore-forming, motile bacterium with the ability to produce the neurotoxin botulinum.
The cumene process is an industrial process for synthesizing phenol and acetone from benzene and propylene. The term stems from cumene, the intermediate material during the process. It was invented by R. Ūdris and P. Sergeyev in 1942 (USSR), and independently by Heinrich Hock in 1944.
Clostridium perfringens is a Gram-positive, bacillus (rod-shaped), anaerobic, spore-forming pathogenic bacterium of the genus Clostridium. C. perfringens is ever-present in nature and can be found as a normal component of decaying vegetation, marine sediment, the intestinal tract of humans and other vertebrates, insects, and soil. It has the shortest reported generation time of any organism at 6.3 minutes in thioglycolate medium.
Acenaphthene is a polycyclic aromatic hydrocarbon (PAH) consisting of naphthalene with an ethylene bridge connecting positions 1 and 8. It is a colourless solid. Coal tar consists of about 0.3% of this compound.
Acenaphthylene, a polycyclic aromatic hydrocarbon is an ortho- and peri-fused tricyclic hydrocarbon. The molecule resembles naphthalene with positions 1 and 8 connected by a -CH=CH- unit. It is a yellow solid. Unlike many polycyclic aromatic hydrocarbons, it has no fluorescence.
In organic chemistry, quaternary ammonium cations, also known as quats, are positively-charged polyatomic ions of the structure [NR4]+, where R is an alkyl group, an aryl group or organyl group. Unlike the ammonium ion and the primary, secondary, or tertiary ammonium cations, the quaternary ammonium cations are permanently charged, independent of the pH of their solution. Quaternary ammonium salts or quaternary ammonium compounds are salts of quaternary ammonium cations. Polyquats are a variety of engineered polymer forms which provide multiple quat molecules within a larger molecule.
The Clostridia are a highly polyphyletic class of Bacillota, including Clostridium and other similar genera. They are distinguished from the Bacilli by lacking aerobic respiration. They are obligate anaerobes and oxygen is toxic to them. Species of the class Clostridia are often but not always Gram-positive and have the ability to form spores. Studies show they are not a monophyletic group, and their relationships are not entirely certain. Currently, most are placed in a single order called Clostridiales, but this is not a natural group and is likely to be redefined in the future.
In chemistry, a dehydration reaction is a chemical reaction that involves the loss of water from the reacting molecule or ion. Dehydration reactions are common processes, the reverse of a hydration reaction.
The oligodynamic effect is a biocidal effect of metals, especially heavy metals, that occurs even in low concentrations. This effect is attributed to the antibacterial behavior of metal ions, which are absorbed by bacteria upon contact and damage their cell membranes.
Gas gangrene is a bacterial infection that produces tissue gas in gangrene. This deadly form of gangrene usually is caused by Clostridium perfringens bacteria. About 1,000 cases of gas gangrene are reported yearly in the United States.
Synthetic resins are industrially produced resins, typically viscous substances that convert into rigid polymers by the process of curing. In order to undergo curing, resins typically contain reactive end groups, such as acrylates or epoxides. Some synthetic resins have properties similar to natural plant resins, but many do not.
1,3-Propanediol is the organic compound with the formula CH2(CH2OH)2. This 3-carbon diol is a colorless viscous liquid that is miscible with water.
Clostridium tetani is a common soil bacterium and the causative agent of tetanus. Vegetative cells of Clostridium tetani are usually rod-shaped and up to 2.5 μm long, but they become enlarged and tennis racket- or drumstick-shaped when forming spores. C. tetani spores are extremely hardy and can be found globally in soil or in the gastrointestinal tract of animals. If inoculated into a wound, C. tetani can grow and produce a potent toxin, tetanospasmin, which interferes with motor neurons, causing tetanus. The toxin's action can be prevented with tetanus toxoid vaccines, which are often administered to children worldwide.
Clostridium butyricum is a strictly anaerobic endospore-forming Gram-positive butyric acid–producing bacillus subsisting by means of fermentation using an intracellularly accumulated amylopectin-like α-polyglucan (granulose) as a substrate. It is uncommonly reported as a human pathogen and is widely used as a probiotic in Japan, Korea, and China. C. butyricum is a soil inhabitant in various parts of the world, has been cultured from the stool of healthy children and adults, and is common in soured milk and cheeses. The connection with dairy products is shown by the name, the butyr- in butyricum reflects the relevance of butyric acid in the bacteria's metabolism and the connection with Latin butyrum and Greek βούτυρον, with word roots pertaining to butter and cheese.
Émile Pierre-Marie van Ermengem (1851–1932) was a Belgian bacteriologist who, in 1895, isolated Clostridium botulinum, the bacterium that causes botulism, from a piece of ham that had poisoned thirty-four people.
Clostridium novyi (oedematiens) a Gram-positive, endospore- forming, obligate anaerobic bacteria of the class Clostridia. It is ubiquitous, being found in the soil and faeces. It is pathogenic, causing a wide variety of diseases in humans and animals.
Hathewaya histolytica is a species of bacteria found in feces and the soil. It is a motile, gram-positive, aerotolerant anaerobe. H. histolytica is pathogenic in many species, including guinea pigs, mice, and rabbits, and humans. H. histolytica has been shown to cause gas gangrene, often in association with other bacteria species.
Clostridium innocuum is an anaerobic, non-motile, gram-positive bacterium that reproduces by sporulation. While there are over 130 species of Clostridium, C. innocuum is the third most commonly isolated. Although it is not normally considered an aggressive human pathogen, it has been isolated in some disease processes. C. innocuum and other Clostridium line the oropharynx and gastrointestinal tract, and are considered normal gut flora.
Clostridium cadaveris is an enteric, gas-forming, motile, strictly anaerobic gram-positive bacterium of the genus Clostridium. First described by Klein in 1899, it was noted to be the most prominent bacteria during human decomposition; historically it was described as "putrefying flora".
4-Chlorophenol is an organic compound with the formula C6H4ClOH. It is one of three monochlorophenol isomers. It is a colorless or white solid that melts easily and exhibits significant solubility in water. Its pKa is 9.14.