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6183659 
Book/Book Chapter 
Archaeal Genetics 
Leigh, JA; Whitman, WB 
2013 
Academic Press 
San Diego 
Brenner's Encyclopedia of Genetics (Second Edition) 
188-191 
The discovery of Archaea in the late 1970s revolutionized our view of life. We now know that life consists of three domains: the Archaea, the Bacteria, and the Eukarya. The first two domains are prokaryotic, although many cellular and molecular features distinguish the Archaea from both Bacteria and Eukarya. Many Archaea thrive in extreme habitats such as hot springs and salt lakes and are extreme thermophiles or halophiles, although non-extremophilic species are also well known. The Archaea consist of three recognized phyla, plus species that have not been officially classified. The phylum Crenarchaeota contains organisms of various metabolic types including hydrogen and sulfur metabolizers, and includes the most extreme of hyperthermophiles with growth optima at 106°C. The phylum Euryarchaeota contains the methanogens (strict anaerobes that reduce single-carbon moieties to methane), the extreme halophiles, and a variety of thermophilic and acidophilic species. The establishment of a third phylum, Thaumarchaeota, has been proposed to accommodate a widespread group of Archaea recently found to oxidize ammonia. Genetic tools have been developed for several species of Archaea, which have emerged as experimentally tractable model organisms. 
Archaea; Crenarchaeota; Euryarchaeota; Halophiles; Hyperthermophiles; Last universal common ancestor; Methanogens; Thaumarchaeota 
Maloy, Stanley