Definição e significado de Spirochaete

Spirochaetes
Spirochaetes.  Numbered ticks are 11 µm apart.  Gram-stained.
Treponema pallidum spirochaetes.
Scientific classification
Domain:	Bacteria
Phylum:	Spirochaetes
Class:	Spirochaetes Cavalier-Smith 2002
Order:	Spirochaetales Buchanan 1917
Families & Genera
?Exilispira Imachi et al. 2008 Brevinemataceae Paster 2012 Brevinema Defosse et al. 1995 Brachyspiraceae Paster 2012 Brachyspira Hovind-Hougen et al. 1983 Leptospiraceae Hovind-Hougen 1979 emend. Levett et al. 2005 Leptonema Hovind-Hougen 1983 Leptospira Noguchi 1917 emend. Faine and Stallman 1982 Turneriella Levett et al. 2005 Spirochaetaceae Swellengrebel 1907 Borrelia Swellengrebel 1907 Clevelandina ♦ Bermudes et al. 1988 Cristispira ♪ Gross 1910 Diplocalyx ♦ (ex Gharagozlou 1968) Bermudes et al. 1988 Hollandina ♦ (ex To et al. 1978) Bermudes et al. 1988 Pillotina ♦ (ex Hollande and Gharagozlou 1967) Bermudes et al. 1988 Sphaerochaeta Ritalahti et al. 2012 Spirochaeta Spirochaeta Ehrenberg 1835 emend. Pikuta et al. 2009 Spironema ♠ Turk et al. 1999 Treponema Schaudinn 1905

  Cross section of a spirochaete cell

Spirochaetes (also spelled spirochetes) belong to a phylum of distinctive diderm (double-membrane) bacteria, most of which have long, helically coiled (spiral-shaped) cells.^[1] Spirochaetes 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 bacterial inner membrane and outer membrane in periplasmic space. 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.

  Classification

The spirochaetes 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, B. garinii, and B. afzelii, which cause Lyme disease
• Borrelia recurrentis, which causes relapsing fever^[3]
• Treponema pallidum subspecies pallidum, which causes syphilis
• Treponema pallidum subspecies pertenue, which causes yaws
• Brachyspira pilosicoli and Brachyspira aalborgi, which cause intestinal spirochetosis^[4]

Cavalier-Smith has postulated that the Spirochaetes belong in a larger clade called Gracilicutes.^[5]

  Phylogeny

The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) ^[6] and National Center for Biotechnology Information (NCBI)^[7] and the phylogeny is based on 16S rRNA-based LTP release 106 by 'The All-Species Living Tree' Project ^[8]

Notes:
♦ Type strain lost or not available
♪ Prokaryotes where no pure (axenic) cultures are isolated or available, i. e. not cultivated or can not be sustained in culture for more than a few serial passages
♠ Strains found at the National Center for Biotechnology Information (NCBI) but not listed in the List of Prokaryotic names with Standing in Nomenclature (LSPN)

  Historical

Salvarsan, the first partially organic antimicrobial drug in medical history, was effective against spirochaetes only and was primarily used to cure syphilis.

  See also

• Flagellum
• Treponema pallidum
• Lyme disease microbiology
• Borrelia
• Bacteriology
• Prokaryote

  References

  External links

• Introduction to the Spirochetes University of California Museum of Paleontology (UCMP)