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n. pl. ar·chae·a (-kē-ə)
Any of various prokaryotic microorganisms of the domain Archaea, being genetically distinct from bacteria and often living in habitats with extreme environmental conditions such as high temperature or salinity. Also called archaebacterium.

[New Latin Archaeon (back-formed singular of Archaea, domain name), from Greek arkhaion, neuter singular of arkhaios, ancient (in reference to the very ancient separation of the archaea and the eubacteria in evolutionary history); see archaic.]


Plural archaea
Any of a group of microorganisms that resemble bacteria but are different from them in certain aspects of their chemical structure, such as the composition of their cell walls. Archaea usually live in extreme environments, such as very hot or salty ones. The archaea are considered a separate kingdom in some classification systems, but a division of the prokaryotes in others. Also called archaebacterium.
References in periodicals archive ?
As the Archaeon watches, animals across the globe are infected with human emotions, a toxic disease resulting in behavioral change at a cellular level.
Identification of 86 candidates for small nonmessenger rnas from the archaeon archaeoglobus fulgidus.
A novel thermostable esterase from the thermoacidophilic archaeon Sulfolobus tokodaii strain 7.
He describes how these constraints affected the later evolution of cells and kept bacteria and archaea simple organisms, and how an endosymbiosis in which one bacterium got inside an archaeon broke those constraints and enabled the evolution of more complex cells, and why it only happened once.
37) In addition to bacteria, the source of methane generation in SIBO is the archaeon Methanobrevibacter smithii.
a Novel Hyperthermophilic Archaeon Capable of Oxidizing Organic Acids and Arowing Autotrophically on Hydrogen with Fe(III) Serving as the Sole Electron Acceptor.
At present, the most widely accepted theory is that mitochondria derive from a bacterium that was engulfed by an archaeon (plural = archaea), a kind of prokaryote that looks similar to a bacterium but has many molecular differences.
The catalase and superoxide dismutase genes are transcriptionally up-regulated upon oxidative stress in the strictly anaerobic archaeon Methanosarcina barkeri.
Pan-genome of the dominant human gut-associated archaeon, Methanobrevibacter smithii, studied in twins.
Konneke M, Bernhard AE, De la Torre JR, Walker CB, Waterbury JB, Stahl DA (2005) Isolation of an autotrophic ammonia-oxidizing marine archaeon.
JARRELL (2005): <<Site-directed Mutagenesis Analysis of Amino Acids Critical for Activity of the Type I Signal Peptidase of the Archaeon Methanococcus voltae>>, Journal of Bacteriology, vol.