Spirochaete
From Wikipedia, the free encyclopedia
| Spirochaetes | |
|---|---|
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| Treponema pallidum spirochetes. | |
| Scientific classification | |
| Domain: | Bacteria |
| Phylum: | Spirochaetes |
| Class: | Spirochaetes |
| Order: | Spirochaetales Buchanan 1917 |
| Families | |
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Spirochaetaceae |
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Spirochaetes (also spelled Spirochetes) belong to a phylum of distinctive Gram-negative bacteria, which have long, helically coiled (spiral-shaped) cells.[1] Spirochetes are chemoheterotrophic in nature, with lengths between 5 and 250 µm and diameters around 0.1-0.6 µm.[citation needed]
Spirochaetes are distinguished from other bacterial phyla by the location of their flagella, sometimes called axial filaments, which run lengthwise between the cell wall and outer membrane. These cause a twisting motion which allows the spirochaete to move about. When reproducing, a spirochaete will undergo asexual transverse binary fission.
Most spirochaetes are free-living and anaerobic, but there are numerous exceptions.
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[edit] Classification
The spirochetes are divided into three families (Brachyspiraceae, Leptospiraceae, and Spirochaetaceae), all placed within a single order (Spirochaetales). Disease-causing members of this phylum include the following:
- Leptospira species, which causes leptospirosis[2]
- Borrelia burgdorferi, which causes Lyme disease
- Borrelia recurrentis, which causes relapsing fever[3]
- Treponema pallidum, which causes syphilis
- Treponema pertenue, which causes yaws
Cavalier-Smith has postulated that the Spirochaetes belong in a larger clade called Gracilicutes.[4]
[edit] Historical
Salvarsan, the first antibiotic in medical history, was effective against spirochaetes only and was primarily used to cure syphilis.
It has been suggested by biologist Lynn Margulis that eukaryotic flagella were derived from symbiotic spirochaetes,[5] but few biologists accept this, as there is no close structural similarity between the two.
[edit] See also
[edit] References
- ^ Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. ISBN 0838585299.
- ^ McBride A, Athanazio D, Reis M, Ko A (2005). "Leptospirosis". Curr Opin Infect Dis 18 (5): 376–86. doi:. PMID 16148523.
- ^ Schwan T (1996). "Ticks and Borrelia: model systems for investigating pathogen-arthropod interactions". Infect Agents Dis 5 (3): 167–81. PMID 8805079.
- ^ Cavalier-Smith, T (2006). "Rooting the tree of life by transition analyses". Biology Direct 1 (19): 19. doi:. PMID 16834776.
- ^ Margulis, L., M. F. Dolan and R. Guerrero. 2000. The chimeric eukaryote: origin of the nucleus from the karyomastigont in amitochondriate protists. PNAS 97: 6954-6959
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