Haloquadratum (common abbreviation: Hqr.) is a genus of archaean, belonging to the family Haloferacaceae.[1] The first species to be identified in this group, Haloquadratum walsbyi, is unusual in that its cells are shaped like square, flat boxes.[2]
This halophilic archaean, discovered in 1980 by A.E. Walsby in the Gavish Sabkha,[3] a coastal hypersaline pool (sabkha) on the Sinai Peninsula in Egypt, was not cultured until 2004.[4]
The cells typically contain polyhydroxyalkanoate (PHA) granules, as well as large numbers of refractile, gas-filled vacuoles which provide buoyancy in a watery environment and may help to position the cells to maximize light-harvesting.[5] The cells may join with others to form fragile sheets up to 40 micrometres wide.
H. walsbyi can be found anywhere[citation needed] in hypersaline waters. When sea water evaporates, high concentration and precipitation of calcium carbonate and calcium sulfate result, leading to a hypersaline sodium chloride-rich brine. Further evaporation results in the precipitation of sodium chloride or halite, and then to a concentrated magnesium chloride brine termed bittern. During the final stage of halite formation, before magnesium chloride concentration causes the brine to become sterile, H. walsbyi flourishes and can make up 80% of the brine's biomass.
^See the NCBI webpage on Haloquadratum. Data extracted from the "NCBI taxonomy resources". National Center for Biotechnology Information. Retrieved 2007-03-19.
^Stoeckenius W (1 October 1981). "Walsby's square bacterium: fine structure of an orthogonal procaryote". J. Bacteriol. 148 (1): 352–60. doi:10.1128/JB.148.1.352-360.1981. PMC 216199. PMID 7287626.
^Walsby, A. E. (1980). "A square bacterium". Nature. 283 (5742): 69–71. Bibcode:1980Natur.283...69W. doi:10.1038/283069a0. S2CID 4341717.
^Cite error: The named reference Burns2007 was invoked but never defined (see the help page).
^Oren A, Pri-El N, Shapiro O, Siboni N (2006). "Buoyancy studies in natural communities of square gas-vacuolate archaea in saltern crystallizer ponds". Saline Systems. 2: 4. doi:10.1186/1746-1448-2-4. PMC 1459177. PMID 16613609.
Haloquadratum walsbyi is a species of Archaea in the genus Haloquadratum, known for its square shape and halophilic nature. First discovered in a brine...
Haloquadratum (common abbreviation: Hqr.) is a genus of archaean, belonging to the family Haloferacaceae. The first species to be identified in this group...
archaea have very different shapes, such as the flat and square cells of Haloquadratum walsbyi. Despite this morphological similarity to bacteria, archaea...
morphologies (the square, flat box-shaped cells of the Archaean genus Haloquadratum). Other arrangements include pairs, tetrads, clusters, chains and palisades...
archaea have very different shapes, such as the flat, square cells of Haloquadratum walsbyi. Despite this morphological similarity to bacteria, archaea...
conducted extensive microbiome and metagenomic DNA sequencing and detected Haloquadratum, Haloferax, Salinibacter, Halobacterium, Halogeometricum, and several...
as well as a precursor to vitamin A. Alongside is the haloarchaeon, Haloquadratum walsbyi, which has flat square-shaped cells with gas vesicles that allow...
shares many properties with halophilic Archaea such as Halobacterium and Haloquadratum that inhabit the same environments. Phenotypically, Salinibacter is...
from the hypersaline Lake Tyrrell, Victoria, Australia. Alongside are small haloarchaeons, Haloquadratum walsbyi, with their flat square-shaped cells....
shapes ranging from flattened triangles in Haloarcula to squares in Haloquadratum, and Natronorubrum. Most species of Halobacteriaceae are best known...
have very strange shapes, such as the flat and square-shaped cells of Haloquadratum walsbyi. Despite this morphological similarity to bacteria, archaea...
special names such as Quin's oval (Quinella ovalis) and Walsby's square (Haloquadratum walsbyi). Before the advent of molecular phylogeny, many higher taxonomic...
have very strange shapes, such as the flat and square-shaped cells of Haloquadratum walsbyi. Despite this morphological similarity to bacteria, archaea...
have very strange shapes, such as the flat and square-shaped cells of Haloquadratum walsbyi. Despite this morphological similarity to bacteria, archaea...
quadrata was first isolated when researchers were attempting to culture Haloquadratum walsbyi, a haloarchaeon that was thought to be unculturable until 2004...
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