Nanobdellati (syn. "DPANN") is a kingdom of archaea first proposed in 2013.
"DPANN" is an acronym formed by the initials of the first five groups discovered: Diapherotrites, Parvarchaeota, Aenigmarchaeota, Nanoarchaeota and Nanohaloarchaeota. Later Woesearchaeota and Pacearchaeota were discovered and proposed within the "DPANN" Phylum.
The Nanobdellati groups together different phyla with a variety of environmental distribution and metabolism, ranging from symbiotic and thermophilic forms such as Nanoarchaeota, like Parvarchaeota and non-extremophiles like Aenigmarchaeota and Diapherotrites. Nanobdellati was also detected in nitrate-rich groundwater, on the water surface but not below, indicating that these taxa are still quite difficult to locate.
Since the recognition of the kingdom rank by the ICNP, the only validly published name for this group is kingdom Nanobdellati.
Characteristics
They are characterized by being small in size compared to other
archaea (nanometric size) and in keeping with their small
genome, they have limited but sufficient catabolic capacities to lead a free life, although many are thought to be
episymbionts that depend on a
symbiotic or parasitic association with other organisms. Many of their characteristics are similar or analogous to those of ultra-small bacteria (CPR group).
Limited metabolic capacities are a product of the small genome and are reflected in the fact that many lack central biosynthetic pathways for nucleotides, aminoacids, and lipids; hence most Nanobdellati archaea, such as ARMAN archaea, which rely on other microbes to meet their biological requirements. But those that have the potential to live freely are fermentative and Aerobic organism heterotrophs.
They are mostly anaerobic and have not been cultivated. They live in extreme environments such as thermophilic, hyperacidophilic, hyperhalophilic or metal-resistant; or also in the temperate environment of marine and lake sediments. They are rarely found on the ground or in the open ocean.
Classification
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Diapherotrites. Found by phylogenetic analysis of the genomes recovered from the groundwater filtration of a gold mine abandoned in the USA.
[ Genomes Online Database]
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Parvarchaeota and Micrarchaeota. Discovered in 2006 in acidic mine drainage from a US mine.
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Woesearchaeota and Pacearchaeota. They have been identified both in sediments and in surface waters of Aquifer and Lake, abounding especially in saline conditions.
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Aenigmarchaeota. Found in wastewater from mines and in sediments from hot springs.
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Nanohalarchaeota. Distributed in environments with high salinity.
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Nanoarchaeota. They were the first discovered (in 2002) in a hydrothermal source next to the coast of Iceland. They live as symbionts of other archaea.
Phylogeny
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Nanobdellati may be the first divergent clade of archaea according to some phylogenetic analyses. Recent phylogenetic analyses have found the following phylogeny between phyla. | Other phylogenetic analyzes have suggested that Nanobdellati could belong to Euryarchaeota or that it may even be polyphyletic occupying different positions within Euryarchaeota. It is also debated whether the phylum Altiarchaeota should be classified in Nanobdellati or Euryarchaeota.[Nina Dombrowski, Jun-Hoe Lee, Tom A Williams, Pierre Offre, Anja Spang (2019). Genomic diversity, lifestyles and evolutionary origins of DPANN archaea. Nature.] An alternative location for Nanobdellati in the phylogenetic tree is as follows.[Jordan T. Bird, Brett J. Baker, Alexander J. Probst, Mircea Podar, Karen G. Lloyd (2017). Culture Independent Genomic Comparisons Reveal Environmental Adaptations for Altiarchaeales. Frontiers.][ The groups marked in quotes are lineages assigned to Nanobdellati, but phylogenetically separated from the rest.
] |
Taxonomy
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN)
and National Center for Biotechnology Information (NCBI).
Kingdom Nanobdellati Rinke et al. 2013
See also
