The Proteobacteria are a major group (phylum) of bacteria. They include a wide variety of pathogens, such as Escherichia, Salmonella, Vibrio, Helicobacter, and many other notable genera. [2] Others are free-living, and include many of the bacteria responsible for nitrogen fixation.
In 1987, Carl Woese established this grouping, calling it informally the "purple bacteria and their relatives".[3] Because of the great diversity of forms found in this group, the Proteobacteria are named after Proteus, a Greek god of the sea, capable of assuming many different shapes, and it is therefore not named after the genus Proteus.[1] [4]
Characteristics [edit]
All proteobacteria are Gram-negative, with an outer membrane mainly composed of lipopolysaccharides. Many move about using flagella, but some are nonmotile or rely on bacterial gliding. The last include the myxobacteria, a unique group of bacteria that can aggregate to form multicellular fruiting bodies. There is also a wide variety in the types of metabolism. Most members are facultatively or obligately anaerobic, chemoautotrophs, and heterotrophic, but there are numerous exceptions. A variety of genera, which are not closely related to each other, convert energy from light through photosynthesis. These are called purple bacteria, referring to their mostly reddish pigmentation.
Taxonomy [edit]
| Phylogeny of Proteobacteria |
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Acidobacteria
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Deltaproteobacteria
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Epsilonbacteria
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Alphaproteobacteria
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Zetaproteobacteria
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Gammaproteobacteria
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Betaproteobacteria
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| Phylogeny of proteobacteria according to ARB living tree, iTOL, Bergey's and others. |
The group is defined primarily in terms of ribosomal RNA (rRNA) sequences. The Proteobacteria are divided into six sections, referred to by the Greek letters alpha through zeta, again based on rRNA sequences. These are often treated as classes. The alpha, beta, delta, epsilon sections are monophyletic,[5][6][7] bar the Gammaproteobacteria due to the Acidithiobacillus genus is paraphyletic to Betaproteobacteria, according to multigenome alignment studies, which if done correctly are more precise than 16S[8] (note that Mariprofundus ferrooxydans sole member of the non-validly published "Zetaproteobacteria"[9] was previously misclassified on NCBI taxonomy). It should be noted that the genera Acidithiobacillus and Thermithiobacillus have been moved to a new Class within the Proteobacteria as of 2013 - the Acidithiobacillia.[10] The divisions of the Proteobacteria were once regarded as subclasses (e.g. α-subclass of the Proteobacteria), but are now regarded as classes (e.g. the Alphaproteobacteria).[11] The naming convention is that each Class is styled in italics with a capital first letter.[11]
References [edit]
- ^ a b Stackebrandt et al. Proteobacteria classis nov., a name for the phylogenetic taxon that includes the "purple bacteria and their relatives". Int. J. Syst. Bacteriol., 1988, 38, 321–325.
- ^ Madigan M; Martinko J (editors). (2005). Brock Biology of Microorganisms (11th ed.). Prentice Hall. ISBN 0-13-144329-1.
- ^ Woese, C. R. (1987). "Bacterial evolution". Microbiological reviews 51 (2): 221–271. PMC 373105. PMID 2439888. edit
- ^ "Proteobacteria". Discover Life: Tree of Life. Retrieved 2007-02-09.
- ^ Noel R. Krieg, Don J. Brenner, James T. Staley (2005). Bergey's manual of systematic bacteriology: The proteobacteria. Springer. ISBN 978-0-387-95040-2.
- ^ Ciccarelli, F. D.; Doerks, T; Von Mering, C; Creevey, CJ; Snel, B; Bork, P (2006). "Toward Automatic Reconstruction of a Highly Resolved Tree of Life". Science 311 (5765): 1283–1287. Bibcode:2006Sci...311.1283C. doi:10.1126/science.1123061. PMID 16513982. edit
- ^ Yarza, P.; Ludwig, W.; Euzéby, J.; Amann, R.; Schleifer, K. H.; Glöckner, F. O.; Rosselló-Móra, R. (2010). "Update of the All-Species Living Tree Project based on 16S and 23S rRNA sequence analyses". Systematic and Applied Microbiology 33 (6): 291–299. doi:10.1016/j.syapm.2010.08.001. PMID 20817437. edit
- ^ Williams, K. P.; Gillespie, J. J.; Sobral, B. W. S.; Nordberg, E. K.; Snyder, E. E.; Shallom, J. M.; Dickerman, A. W. (2010). "Phylogeny of Gammaproteobacteria". Journal of Bacteriology 192 (9): 2305–2314. doi:10.1128/JB.01480-09. PMC 2863478. PMID 20207755. edit
- ^ Emerson, David; Rentz, Jeremy A.; Lilburn, Timothy G.; Davis, Richard E.; Aldrich, Henry; Chan, Clara; Moyer, Craig L. (2007). "A Novel Lineage of Proteobacteria Involved in Formation of Marine Fe-Oxidizing Microbial Mat Communities". In Reysenbach, Anna-Louise. PLoS ONE 2 (8): e667. Bibcode:2007PLoSO...2..667E. doi:10.1371/journal.pone.0000667. edit
- ^ Williams KP, Kelly DP (2013) Proposal for a new Class within the Proteobacteria, the Acidithiobacillia, with the Acidithiobacillales as the type Order. International Journal of Systematic and Evolutionary Microbiology. Published online, January 2013
- ^ a b Lee at al. Int J Syst Evol Microbiol 55 (2005), 1907–1919.
External links [edit]
