Girish Mahajan (Editor)


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Scientific name

Higher classification




Haloarchaea Deep Lake Biofilm forming Haloarchaea

Archaeans, Halobacterium, Haloferax, Haloarcula, Halobacterium salinarum

Halobacteria (also Halobacteriacea) are a class of the Euryarchaeota, found in water saturated or nearly saturated with salt. Halobacteria are now recognized as archaea, rather than bacteria. The name 'halobacteria' was assigned to this group of organisms before the existence of the domain Archaea was realized, and remains valid according to taxonomic rules. In a non-taxonomic context, halophilic archaea are referred to as haloarchaea to distinguish them from halophilic bacteria.


Haloarchaea Papke Lab at the University of Connecticut Archaea

These microorganisms are members of the halophile community, in that they require high salt concentrations to grow. They are a distinct evolutionary branch of the Archaea, and are generally considered extremophiles, although not all members of this group can be regarded as such.

Haloarchaea Synthetic Biology Facciotti Lab

Haloarchaea can grow aerobically or anaerobically. Parts of the membranes of haloarchaea are purplish in color, and large blooms of haloarchaea appear reddish, from the pigment bacteriorhodopsin, related to the retinal pigment rhodopsin which it uses to transform light energy into chemical energy by a process unrelated to chlorophyll-based photosynthesis.

Haloarchaea httpsiytimgcomviFgJ4yrmW6V4hqdefaultjpg

Haloarchaea have a potential to solubilized phosphorus. P- solubilizing halophilic archaea may play a role in P nutrition to vegetation growing in hypersaline soils. Haloarchaea may have application as inoculants for crop growing in hypersaline regions.

Haloarchaea Deep Lake Biofilm forming Haloarchaea


Haloarchaea Ravelry Haloarchaea Mitts pattern by Virginia Catherall

The extremely halophilic, aerobic members of Archaea are classified within the family Halobacteriaceae, order Halobacteriales in Class III. Halobacteria of the phylum Euryarchaeota (International Committee on Systematics of Prokaryotes, Subcommittee on the taxonomy of Halobacteriaceae). As of May 2016, the family Halobacteriaceae comprises 50 genera 213 species.

Domain : Archaea


  • Halobacteria
  • Halobacteriales
  • Halobacteriaceae
  • Haladaptatus [Hap.]
  • Haladaptatus cibarius
  • Haladaptatus litoreus
  • Haladaptatus pallidirubidus
  • Haladaptatus paucihalophilus (Type species)
  • Halalkalicoccus [Hac.]
  • Halalkalicoccus jeotgali
  • Halalkalicoccus paucihalophilus
  • Halalkalicoccus tibetensis (Type species)
  • "Halanaeroarchaeum" ["Haa".]
  • "Halanaeroarchaeum sulfurireducens" (Type species) (IJSEM, in press)
  • Halapricum [Hpr.]
  • Halapricum salinum (Type species)
  • Halarchaeum [Hla.]
  • Halarchaeum acidiphilum (Type species)
  • Halarchaeum grantii
  • Halarchaeum nitratireducens
  • Halarchaeum rubridurum
  • Halarchaeum salinum
  • Halarchaeum solikamskense
  • Haloarchaeobius [Hab.]
  • Haloarchaeobius amylolyticus
  • Haloarchaeobius baliensis
  • Haloarchaeobius iranensis (Type species)
  • Haloarchaeobius litoreus
  • Haloarchaeobius salinus
  • Haloarcula [Har.]
  • Haloarcula amylolytica
  • Haloarcula argentinensis
  • Haloarcula hispanica
  • Haloarcula japonica
  • Haloarcula marismortui
  • Haloarcula quadrata
  • Haloarcula salaria
  • Haloarcula tradensis
  • Haloarcula vallismortis (Type species)
  • Halobacterium [Hbt.] (Type genus)
  • Halobacterium jilantaiense
  • Halobacterium noricense
  • "Halobacterium piscisalsi" (subjective junior synonym of Halobacterium salinarum)
  • Halobacterium ruburm
  • Halobacterium salinarum (Type species)
  • Halobaculum [Hbl.]
  • Halobaculum gomorrense (Type species)
  • Halobaculum magnesiiphilum
  • Halobellus [Hbs.]
  • Halobellus clavatus (Type species)
  • Halobellus inordinatus
  • Halobellus limi
  • Halobellus litoreus
  • Halobellus ramosii
  • Halobellus rarus
  • Halobellus rufus
  • Halobellus salinus
  • Halobiforma [Hbf.]
  • Halobiforma haloterrestris (Type species)
  • Halobiforma lacisalsi
  • Halobiforma nitratireducens
  • Halocalculus [Hcl.]
  • Halocalculus aciditolerans (Type species)
  • Halococcus [Hcc.]
  • Halococcus agarilyticus
  • Halococcus dombrowskii
  • Halococcus hamelinensis
  • Halococcus morrhuae (Type species)
  • Halococcus qingdaonensis
  • Halococcus saccharolyticus
  • Halococcus salifodinae
  • Halococcus sediminicola
  • Halococcus thailandensis
  • Haloferax [Hfx.]
  • Haloferax alexandrinus
  • Haloferax chudinovii
  • Haloferax denitrificans
  • Haloferax elongans
  • Haloferax gibbonsii
  • Haloferax larsenii
  • Haloferax lucentense
  • Haloferax mediterranei
  • Haloferax mucosum
  • Haloferax prahovense
  • Haloferax sulfurifontis
  • Haloferax volcanii (Type species)
  • Halogeometricum [Hgm.]
  • Halogeometricum borinquense (Type species)
  • Halogeometricum limi
  • Halogeometricum pallidum
  • Halogeometricum rufum
  • Halogranum [Hgn.]
  • Halogranum amylolyticum
  • Halogranum gelatinilyticum
  • Halogranum rubrum (Type species)
  • Halogranum salarium
  • Halohasta [Hht.]
  • Halohasta litorea (Type species)
  • Halohasta litchfieldiae
  • Halolamina [Hlm.]
  • Halolamina pelagica (Type species)
  • Halolamina rubra
  • Halolamina salifodinae
  • Halolamina salina
  • Halolamina sediminis
  • Halomarina [Hmr.]
  • Halomarina oriensis (Type species)
  • Halomicroarcula [Hma.]
  • Halomicroarcula limicola
  • Halomicroarcula pellucida (Type species)
  • Halomicroarcula salina
  • Halomicrobium [Hmc.]
  • Halomicrobium katesii
  • Halomicrobium mukohataei (Type species)
  • Halomicrobium zhouii
  • Halonotius [Hns.]
  • Halonotius pteroides (Type species)
  • "Haloparvum" ["Hpv".]
  • "Haloparvum sedimenti" (Type species) (IJSEM, in press)
  • Halopelagius [Hpl.]
  • Halopelagius inordinatus (Type species)
  • Halopelagius fulvigenes
  • Halopelagius longus
  • Halopenitus [Hpt.]
  • Halopenitus malekzadehii
  • Halopenitus persicus (Type species)
  • Halopenitus salinus
  • Halopiger [Hpg.]
  • Halopiger aswanensis
  • Halopiger salifodinae
  • Halopiger xanaduensis (Type species)
  • Haloplanus [Hpn.]
  • Haloplanus aerogenes
  • Haloplanus litoreus
  • Haloplanus natans (Type species)
  • Haloplanus ruber
  • Haloplanus salinus
  • Haloplanus vescus
  • Haloquadratum [Hqr.]
  • Haloquadratum walsbyi (Type species)
  • Halorhabdus [Hrd.]
  • Halorhabdus tiamatea
  • Halorhabdus utahensis (Type species)
  • "Halorhabdus rudnickae" (Syst Appl Microbiol., in press)
  • Halorientalis [Hos.]
  • Halorientalis brevis
  • Halorientalis persicus
  • Halorientalis regularis (Type species)
  • Halorubellus [Hrb.]
  • Halorubellus litoreus
  • Halorubellus salinus (Type species)
  • Halorubrum [Hrr.]
  • Halorubrum aquaticum
  • Halorubrum aidingense
  • Halorubrum alkaliphilum
  • Halorubrum arcis
  • Halorubrum californiense
  • Halorubrum chaoviator
  • Halorubrum cibi
  • Halorubrum coriense
  • Halorubrum distributum
  • Halorubrum ejinorense
  • Halorubrum ezzemoulense
  • Halorubrum gandharaense
  • Halorubrum halodurans
  • Halorubrum halophilum
  • Halorubrum kocurii
  • Halorubrum lacusprofundi
  • Halorubrum laminariae
  • Halorubrum lipolyticum
  • Halorubrum litoreum
  • Halorubrum luteum
  • Halorubrum orientale
  • Halorubrum persicum
  • Halorubrum rubrum
  • "Halorubrum rutilum" (Arch Microbiol.,2015, 197(10):1159-1164)
  • Halorubrum saccharovorum (Type species)
  • Halorubrum salinum
  • Halorubrum sodomense
  • Halorubrum tebenquichense
  • Halorubrum terrestre
  • Halorubrum tibetense
  • Halorubrum trapanicum
  • Halorubrum vacuolatum
  • Halorubrum yunnanense
  • Halorubrum xinjiangense
  • Halorussus [Hrs.]
  • Halorussus amylolyticus
  • Halorussus rarus
  • Halorussus ruber
  • "Halosiccatus" ["Hsc".]
  • "Halosiccatus urmianus" (Type species) (IJSEM, in press)
  • Halosimplex [Hsx.]
  • Halosimplex carlsbadense (Type species)
  • Halosimplex litoreum
  • Halosimplex pelagicum
  • Halosimplex rubrum
  • Halostagnicola [Hst.]
  • Halostagnicola alkaliphila
  • Halostagnicola bangensis
  • Halostagnicola kamekurae
  • Halostagnicola larsenii (Type species)
  • "Halostella" ["Hsl".]
  • "Halostella salina" (Type species) (IJSEM, in press)
  • Haloterrigena [Htg.]
  • Haloterrigena daqingensis
  • Haloterrigena hispanica
  • Haloterrigena jeotgali
  • Haloterrigena limicola
  • Haloterrigena longa
  • Haloterrigena saccharevitans
  • Haloterrigena salina
  • Haloterrigena thermotolerans
  • Haloterrigena turkmenica (Type species)
  • Halovarius [Hvr.]
  • Halovarius luteus (Type species)
  • Halovenus [Hvn.]
  • Halovenus aranensis (Type species)
  • Halovenus rubra
  • Halovenus salina
  • Halovivax [Hvx.]
  • Halovivax asiaticus (Type species)
  • Halovivax cerinus
  • Halovivax limisalsi
  • Halovivax ruber
  • Natrialba [Nab.]
  • Natrialba aegyptia
  • Natrialba asiatica (Type species)
  • Natrialba chahannaoensis
  • Natrialba hulunbeirensis
  • Natrialba magadii
  • Natrialba taiwanensis
  • Natribaculum [Nbl.]
  • Natribaculum breve (Type species)
  • Natribaculum longum
  • Natrinema [Nnm.]
  • Natrinema altunense
  • Natrinema ejinorense
  • Natrinema gari
  • Natrinema pallidum
  • Natrinema pellirubrum (Type species)
  • Natrinema salaciae
  • Natrinema versiforme
  • Natronoarchaeum [Nac.]
  • Natronoarchaeum mannanilyticum (Type species)
  • Natronoarchaeum philippinense
  • Natronoarchaeum rubrum
  • Natronobacterium [Nbt.]
  • Natronobacterium gregoryi (Type species)
  • Natronobacterium texcoconense
  • Natronococcus [Ncc.]
  • Natronococcus amylolyticus
  • Natronococcus jeotgali
  • Natronococcus occultus (Type species)
  • Natronococcus roseus
  • Natronolimnobius [Nln.]
  • Natronolimnobius baerhuensis (Type species)
  • Natronolimnobius innermongolicus
  • Natronomonas [Nmn.]
  • Natronomonas gomsonensis
  • Natronomonas moolapensis
  • Natronomonas pharaonis (Type species)
  • Natronorubrum [Nrr.]
  • Natronorubrum aibiense
  • Natronorubrum bangense (Type species)
  • Natronorubrum sediminis
  • Natronorubrum sulfidifaciens
  • Natronorubrum texcoconense
  • Natronorubrum tibetense
  • Salarchaeum [Sar.]
  • Salarchaeum japonicum (Type species)
  • Salinarchaeum [Saa.]
  • Salinarchaeum laminariae (Type species)
  • Salinigranum [Sgn.]
  • Salinigranum rubrum (Type species)
  • Salinirubrum [Srr.]
  • Salinirubrum litoreum (Type species)
  • non-valid

  • "Halorubrum sfaxense"
  • "Candidatus Halobonum tyrrellensis。
  • "Candidatus Haloectosymbiotes riaformosensis"。
  • "Halopiger djelfamassiliensis sp"
  • "Halopiger goleamassiliensis"
  • "Haloferax namakaokahaiae"'。
  • "Halorubrum tropicale"
  • "Haloarcula rubripromontorii"
  • "Halobacterium hubeiense"
  • Classification of Gupta et al.


  • Halobacteriaceae (Type genera: Halobacterium)
  •   Haladaptatus, Halalkalicoccus, Haloarchaeobius, Halarchaeum, Halobacterium, Halocalculus, Halorubellus, Halorussus, "Halosiccatus", Halovenus, Natronoarchaeum, Natronomonas, Salarchaeum.

  • Haloarculaceae (Type genera: Haloarcula)
  •   Halapricum, Haloarcula, Halomicroarcula, Halomicrobium, Halorientalis, Halorhabdus, Halosimplex.

  • Halococcaceae (Type genera: Halococcus)
  •   Halococcus.


  • Haloferacaceae (Type genera: Haloferax)
  •   Halabellus, Haloferax, Halogeometricum, (Halogranum), Halopelagius, Haloplanus, Haloquadratum, Halosarcina.

  • Halorubraceae (Type genera: Halorubrum)
  •   Halobaculum, (Halogranum), Halohasta, Halolamina, Halonotius, Halopenitus, Halorubrum, Salinigranum.


  • Natrialbaceae (Type genera: Natrialba)
  •   Halobiforma, Halopiger, Halostagnicola, Haloterrigena, Halovarius, Halovivax, Natrialba, Natribaculum, Natronobacterium, Natronococcus, Natronolimnobius, Natronorubrum, Salinarchaeum.

    Living environment

    Haloarchaea require salt concentrations in excess of 2 M (or about 10%) to grow, and optimal growth usually occurs at much higher concentrations, typically 20–25%. However, Haloarchaea can grow up to saturation (about 37% salts).

    Haloarchaea are found mainly in hypersaline lakes and solar salterns. Their high densities in the water often lead to pink or red colourations of the water (the cells possessing high levels of carotenoid pigments, presumably for UV protection).

    Phototrophy in haloarchaea

    Bacteriorhodopsin is used to absorb light, which provides energy to transport protons (H+) across the cellular membrane. The concentration gradient generated from this process can then be used to synthesize ATP. Many haloarchaea also possess related pigments, including halorhodopsin, which pumps chloride ions in the cell 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 haloarchaea are incapable of fixing carbon from carbon dioxide.

    Cellular shapes

    Haloarchaea are often considered pleomorphic, or able to take on a range of shapes—even within a single species. This makes identification by microscopic means difficult, and it is now more common to use gene sequencing techniques for identification instead.

    One of the more unusually shaped Haloarchaea is the "Square Haloarchaeon of Walsby." It was classified in 2004 using a very low nutrition solution to allow growth along with a high salt concentration, square in shape and extremely thin (like a postage stamp). This shape is probably only permitted by the high osmolarity of the water, permitting cell shapes that would be difficult, if not impossible, under other conditions.

    Haloarchaea as Exophiles

    Haloarchaea have been proposed as a kind of life that could live on Mars; since the Martian atmosphere has a pressure below the triple point of water, freshwater species would have no habitat on the Martian surface.


    Haloarchaea Wikipedia