Euryarchaeota (from
Ancient Greekεὐρύς eurús, "broad, wide") is a
phylum of
archaea.[3] Euryarchaeota are highly diverse and include
methanogens, which produce methane and are often found in intestines;
halobacteria, which survive
extreme concentrations of salt; and some extremely
thermophilic aerobes and anaerobes, which generally live at temperatures between 41 and 122 °C. They are separated from the other archaeans based mainly on
rRNA sequences and their unique DNA polymerase.[4]
Description
The Euryarchaeota are diverse in appearance and metabolic properties. The phylum contains organisms of a variety of shapes, including both
rods and
cocci. Euryarchaeota may appear either
gram-positive or gram-negative depending on whether
pseudomurein is present in the cell wall.[5]Euryarchaeota also demonstrate diverse lifestyles, including methanogens, halophiles, sulfate-reducers, and extreme thermophiles in each.[5] Others live in the ocean, suspended with plankton and bacteria. Although these marine euryarchaeota are difficult to culture and study in a lab, genomic sequencing suggests that they are motile
heterotrophs.[6]
Though it was previously thought that euryarchaeota only lived in extreme environments (in terms of temperature, salt content and/or pH), a paper by Korzhenkov et al published in January 2019 showed that euryarchaeota also live in moderate environments, such as low-temperature acidic environments. In some cases, euryarchaeota outnumbered the bacteria present.[7] Euryarchaeota have also been found in other moderate environments such as water springs, marshlands, soil and
rhizospheres.[8] Some euryarchaeota are highly adaptable; an order called
Halobacteriales are usually found in extremely salty and sulfur-rich environments but can also grow in salt concentrations as low as that of seawater 2.5%.[8] In rhizospheres, the presence of euryarchaeota seems to be dependent on that of
mycorrhizalfungi; a higher fungal population was correlated with higher euryarchaeotal frequency and diversity, while absence of mycorrihizal fungi was correlated with absence of euryarchaeota.[8]
Other phylogenetic analyzes have suggested that the archaea of the clade
DPANN may also belong to Euryarchaeota and that they may even be a
polyphyletic group occupying different phylogenetic positions within Euryarchaeota. It is also debated whether the phylum
Altiarchaeota should be classified in DPANN or Euryarchaeota.[14] A cladogram summarizing this proposal is graphed below.[15][16] The groups marked in quotes are lineages assigned to DPANN, but phylogenetically separated from the rest.
^Hogan CM (2010). E. Monosson, C. Cleveland (eds.).
"Archaea". Encyclopedia of Earth. National Council for Science and the Environment. Retrieved 18 August 2017.
^
abcBomberg M, Timonen S (October 2007). "Distribution of cren- and euryarchaeota in scots pine mycorrhizospheres and boreal forest humus". Microbial Ecology. 54 (3): 406–16.
doi:
10.1007/s00248-007-9232-3.
PMID17334967.
S2CID19425171.
Woese CR, Gupta R, Hahn CM, Zillig W, Tu J (1984). "The phylogenetic relationships of three sulfur dependent archaebacteria". Systematic and Applied Microbiology. 5: 97–105.
doi:
10.1016/S0723-2020(84)80054-5.
PMID11541975.