Thaumarchaeota
Encyclopedia
In taxonomy
Alpha taxonomy
Alpha taxonomy is the discipline concerned with finding, describing and naming species of living or fossil organisms. This field is supported by institutions holding collections of these organisms, with relevant data, carefully curated: such institutes include natural history museums, herbaria and...

, the Thaumarchaeota (from the Greek 'thaumas', meaning wonder) are a newly-proposed phylum
Phylum
In biology, a phylum The term was coined by Georges Cuvier from Greek φῦλον phylon, "race, stock," related to φυλή phyle, "tribe, clan." is a taxonomic rank below kingdom and above class. "Phylum" is equivalent to the botanical term division....

 of the Archaea
Archaea
The Archaea are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon...

, containing so far four species, Nitrosopumilus maritimus, Cenarchaeum symbiosum
Cenarchaeum symbiosum
Cenarchaeum symbiosum is a species of Archaebacteria in the genus Cenarchaeum, and is one of the three species contained by the newly proposed phylum Thaumarchaeota in the domain Archaea. C. symbiosum is psychrophilic and is found inhabiting marine sponges.- Genome :The genome of C...

, Nitrososphaera viennensis, and Nitrososphaera gargensis. All organisms of this lineage discovered so far are chemolithoautotrophic ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

-oxidizers and may play important roles in biogeochemical cycle
Biogeochemical cycle
In ecology and Earth science, a biogeochemical cycle or substance turnover or cycling of substances is a pathway by which a chemical element or molecule moves through both biotic and abiotic compartments of Earth. A cycle is a series of change which comes back to the starting point and which can...

s, such as the nitrogen cycle
Nitrogen cycle
The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out by both biological and non-biological processes. Important processes in the nitrogen cycle include fixation, mineralization, nitrification, and denitrification...

 and the carbon cycle
Carbon cycle
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth...

.

The phylum was proposed in 2008 based on phylogenetic data, such as the sequences of these organisms' ribosomal RNA
Ribosomal RNA
Ribosomal ribonucleic acid is the RNA component of the ribosome, the enzyme that is the site of protein synthesis in all living cells. Ribosomal RNA provides a mechanism for decoding mRNA into amino acids and interacts with tRNAs during translation by providing peptidyl transferase activity...

 genes, and the presence of a form of type I topoisomerase
Type I topoisomerase
Type I topoisomerases cut one strand of double-stranded DNA, relax the strand, and reanneal the strands. They are further subdivided into two structurally and mechanistically distinct topoisomerases: type IA and type IB....

 that was previously thought to be unique to the eukaryote
Eukaryote
A eukaryote is an organism whose cells contain complex structures enclosed within membranes. Eukaryotes may more formally be referred to as the taxon Eukarya or Eukaryota. The defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear...

s. This assignment was confirmed by further analysis published in 2010 that examined the genomes of the ammonia-oxidizing archaea Nitrosopumilus maritimus and Nitrososphaera gargensis concluded that these species form a distinct lineage that includes Cenarchaeum symbiosum
Cenarchaeum symbiosum
Cenarchaeum symbiosum is a species of Archaebacteria in the genus Cenarchaeum, and is one of the three species contained by the newly proposed phylum Thaumarchaeota in the domain Archaea. C. symbiosum is psychrophilic and is found inhabiting marine sponges.- Genome :The genome of C...

, which was the first member of the Thaumarchaeota to be described.
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