Spirochaete
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| Image:Treponema pallidum 01.png Treponema pallidum spirochetes.
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Spirochaetaceae |
The spirochaetes (or spirochetes) are a phylum of distinctive bacteria, which have long, helically coiled cells. They are chemoheterotrophic in nature. Their length measures 5-500 nano metre and their diameter measures around 0.1-0.6 nano metre. They are distinguished by the presence of flagella running lengthwise between the cell membrane and cell wall, called axial filaments. These cause a twisting motion which allows the spirochaete to move about. The genome of spirochaetes are also highly unusual and consists of linear chromosomes and plasmids.<ref>Hinnebusch J, Tilly K (1993). "Linear plasmids and chromosomes in bacteria.". Mol Microbiol 10 (5): 917-22. PMID 7934868.</ref> Most spirochaetes are free-living and anaerobic, but there are numerous exceptions.For example Relapsing fever is caused by Borrelia recurrentis and Weil's disease which is caused by Leptospiractero haemorrhagiae.
It has been suggested by Lynn Margulis that eukaryotic flagella were derived from symbiotic spirochaetes, but few biologists accept this, as there is no close structural similarity between the two.
The spirochaetes are divided into three families, all placed within a single order. Important members of this phylum include
- Leptospira species, which causes leptospirosis,
- Borrelia burgdorferi, which causes Lyme disease, and
- Treponema pallidum, which causes syphilis.
Spirochaetes are gram-negative bacteria
[edit] References
<references/>
- Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology, 4th ed., McGraw Hill. ISBN 0-8385-8529-9.
[edit] External links
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