Corynebacterium
Corynebacterium (Greek coryne = lobe) is a genus aerobic to facultative anaerobic living, gram-positive bacteria with high GC content. The representatives are 3-5 microns long, do not form spores and are immobile. As with the mycobacterial mycolic acids are present in their cell wall, suggesting a close relationship.
The genus is diverse; some of these are pathogenic for humans or animals. Others are saprophytes, they live on decaying plant debris. Some non-pathogenic are commonly found in the mucosa and flora on the skin of humans.
Characteristics and detection
A special feature of the cell wall, which serves as indicator for the Corynebacterium, are contained in their meso-2 ,6- Diaminopimelinsäuren, the sugar galactose and arabinose and mycolic acids. In the cytoplasm are stainable granules to find so-called Polkörnchen containing polyphosphates. They are recorded by the Neisser stain. The bacterium appears then colored yellow with dark Polkörnchen at the cell pole. The bacteria can be cultured on blood agar, which is available for the identification of infectious diseases important enzyme catalase. A distinction of the different species can be done by the detection of various metabolic reactions. The presence of the enzyme urease to urea degradation which Cystinabbau, nitrate reduction, glucose fermentation and sucrose are used as criteria.
Cell shape and cell division
The cells of the corynebacteria usually have a characteristic cone shape. The shape formed by a swollen end of the cell. This cell morphology was also eponymous ( koryne is ancient Greek and means " mace "). Generally referred to bacteria whose cells are thickened club-shaped at one end, as " coryneform ". Corynebacterium is pleomorphic, during growth, the shape change between rod- shaped and coccoid.
Often cells remain after the division joined together, they appear under the microscope in a V shape. This is caused by the so-called postfisionäre snapping motion (English: Snapping Postfission Movements ), or simply snap division ( Snapping division). The cell wall consists of two layers in corynebacteria, only the inner participates in cell division, then the outer surrounds the two daughter cells. Shortly after the division breaks the outer one at a limited point. The two cells then move from the side on which the continued disruption took place, they snap apart and now form the distinctive V-shape.
Pathogenicity
Corynebacterium diphtheriae, if it is infected by a specific bacteriophage, cause diphtheria. Among the genes which infiltrates the phage into the bacterium, is a gene encoding the diphtheria toxin. This toxin inhibits ( inhibits ) the protein synthesis in human cells. If the bacterium is not affected by this bacteriophage, it remains harmless. Also, some strains of Corynebacterium ulcerans closely related are able to trigger symptoms of diphtheria.
Another important genus Corynebacterium glutamicum, which is used as a model organism for the study of other pathogenic agents. For industry, it is important, inter alia, as a producer of glutamic acid.
Taxonomy
The corynebacteria are among the Actinobacteria, a group of gram-positive bacteria.
Several ways:
- Corynebacterium afermentans (Riegel et al., 1993)
- Corynebacterium ammoniagenes ( Cooke and Keith 1927) Collins 1987 ( synonym: Brevibacterium ammoniagenes )
- Corynebacterium amycolatum ( Collins et al., 1988)
- Corynebacterium auris ( Funke et al., 1995)
- Corynebacterium atypicum ( Hall et al. 2003)
- Corynebacterium bovis ( Bergey et al., 1923 )
- Corynebacterium callunae (Lee and Good 1963) Yamada and Komagata 1972
- Corynebacterium casei ( Brennan et al. 2001)
- Corynebacterium confusum ( Funke et al. 1998)
- Corynebacterium diphtheriae ( Kruse 1886) Lehmann and Neumann 1896
- Corynebacterium equi ( Magnusson 1923)
- Corynebacterium halotolerans (Chen et al. 2004)
- Corynebacterium hansenii ( Renaud et al., 2007 )
- Corynebacterium glucuronolyticum ( Funke et al., 1995)
- Corynebacterium glutamicum ( Kinoshita et al. 1958), Abe et al. 1967
- Corynebacterium jeikeium ( Jackman et al. 1988)
- Corynebacterium minutissimum (ex Sarkany et al. 1962) Collins and Jones 1983 ( Erythrasma )
- Corynebacterium mycetoides (ex Castellani 1942) Collins 1983
- Corynebacterium pseudotuberculosis ( Buchanan 1911, Eberson 1918)
- Corynebacterium resistens ( Otsuka et al. 2005)
- Corynebacterium striatum ( Chester 1901) Eberson 1918
- Corynebacterium tuscaniense (Riegel et al. 2006)
- Corynebacterium ulcerans (ex Gilbert and Stewart 1927) Riegel et al. 1995
- Corynebacterium urealyticum ( Pitcher et al., 1992) ( Corynebacteria the group D2)
- Corynebacterium xerosis ( Lehmann & Neumann 1896) Lehmann & Neumann 1899