Halobacteriales

Halobacteriales
Scientific classification
Domain:	Archaea
Kingdom:	Euryarchaeota
Phylum:	Euryarchaeota
Class:	Halobacteria
Order:	Halobacteriales Grant & Larsen, 1989
Family
Halobacteriaceae

In taxonomy, the Halobacteriales are an order of the Halobacteria, found in water saturated or nearly saturated with salt. They are also called halophiles, though this name is also used for other organisms which live in somewhat less concentrated salt water. They are common in most environments where large amounts of salt, moisture, and organic material are available. Large blooms appear reddish, from the pigment bacteriorhodopsin. This pigment is used to absorb light, which provides energy to create ATP. Halobacteria also possess a second pigment, halorhodopsin, which pumps in chloride ions in response to photons, creating a voltage gradient and assisting in the production of energy from light. The process is unrelated to other forms of photosynthesis involving electron transport; however, and halobacteria are incapable of fixing carbon from carbon dioxide.

Halobacteria can exist in salty environments because although they are aerobes they have a separate and different way of creating energy through photosynthesis. Parts of the membranes of halobacteria are purplish in color. These parts conduct photosynthetic reactions with retinal pigment rather than chlorophyll. This allows them to create a proton gradient across the membrane of the cell which can be used to create ATP for their own use.

Further reading

Scientific journals

• Wright, A-DG (2006). "Phylogenetic relationships within the order Halobacteriales inferred from 16S rRNA gene sequences". Int. J. Syst. Evol. Microbiol. 56: 1223–1227. doi:10.1099/ijs.0.63776-0. PMID 16738095.

• Judicial Commision of the International Committee on Systematics of Prokaryotes (2005). "The nomenclatural types of the orders Acholeplasmatales, Halanaerobiales, Halobacteriales, Methanobacteriales, Methanococcales, Methanomicrobiales, Planctomycetales, Prochlorales, Sulfolobales, Thermococcales, Thermoproteales and Verrucomicrobiales are the genera Acholeplasma, Halanaerobium, Halobacterium, Methanobacterium, Methanococcus, Methanomicrobium, Planctomyces, Prochloron, Sulfolobus, Thermococcus, Thermoproteus and Verrucomicrobium, respectively. Opinion 79". Int. J. Syst. Evol. Microbiol. 55: 517–518. PMID 15653928.

• Cavalier-Smith, T (2002). "The neomuran origin of archaebacteria, the negibacterial root of the universal tree and bacterial megaclassification". Int. J. Syst. Evol. Microbiol. 52: 7–76. PMID 11837318.

• Euzeby JP, Tindall BJ (2001). "Nomenclatural type of orders: corrections necessary according to Rules 15 and 21a of the Bacteriological Code (1990 Revision), and designation of appropriate nomenclatural types of classes and subclasses. Request for an Opinion". Int. J. Syst. Evol. Microbiol. 51: 725–727. PMID 11321122.

• Cavalier-Smith, T (1986). "The kingdoms of organisms". Nature. 324: 416–417. doi:10.1038/324416a0. PMID 2431320.

Scientific books

• Grant WD, Kamekura M, McGenity TJ, Ventosa A (2001). "Class III. Halobacteria class. nov.". In DR Boone and RW Castenholz, eds. (ed.). Bergey's Manual of Systematic Bacteriology Volume 1: The Archaea and the deeply branching and phototrophic Bacteria (2nd ed. ed.). New York: Springer Verlag. p. 169. ISBN 978-0387987712. {{cite book}}: |edition= has extra text (help); |editor= has generic name (help)CS1 maint: multiple names: authors list (link)

• Grant WD, Larsen H (1989). "Group III. Extremely halophilic archaeobacteria. Order Halobacteriales ord. nov.". In JT Staley, MP Bryant, N Pfennig, and JG Holt, eds. (ed.). Bergey's Manual of Systematic Bacteriology, Volume 3 (1st ed. ed.). Baltimore: The Williams & Wilkins Co. p. 169. {{cite book}}: |edition= has extra text (help); |editor= has generic name (help)CS1 maint: multiple names: editors list (link)