DPANN is a super

phylum In biology, a phylum (; plural: phyla) is a level of classification or taxonomic rank below kingdom and above class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclature ...

Archaea Archaea ( ; singular archaeon ) is a domain of single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially classified as bacteria, receiving the name archaebacteria (in the Archaeba ...

first proposed in 2013. Many members show novel signs of

horizontal gene transfer Horizontal gene transfer (HGT) or lateral gene transfer (LGT) is the movement of genetic material between unicellular and/or multicellular organisms other than by the ("vertical") transmission of DNA from parent to offspring (reproduction). H ...

from other domains of life. They are known as nanoarchaea or ultra-small archaea due to their smaller size (nanometric) compared to other archaea. DPANN is an acronym formed by the initials of the first five groups discovered, Diapherotrites,

Parvarchaeota Parvarchaeota is a phylum of archaea belonging to the DPANN archaea. They have been discovered in acid mine drainage waters and later in marine sediments. The cells of these organisms are extremely small consistent with small genomes. Metagenomi ...

, Aenigmarchaeota,

Nanoarchaeota Nanoarchaeota (Greek, "dwarf or tiny ancient one") are a phylum of the Archaea. This phylum currently has only one representative, ''Nanoarchaeum equitans''. Taxonomy 53 marker proteins based GTDB 07-RS207 phylogeny. The currently accepted ...

and Nanohaloarchaeota. Later Woesearchaeota and Pacearchaeota were discovered and proposed within the DPANN superphylum. In 2017, another phylum Altiarchaeota was placed into this superphylum. The

monophyly In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic ...

of DPANN is not considered established until now, due to the high

mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, m ...

rate of the included phyla, which can lead to the artifact of the

long branch attraction In phylogenetics, long branch attraction (LBA) is a form of systematic error whereby distantly related lineages are incorrectly inferred to be closely related. LBA arises when the amount of molecular or morphological change accumulated within a lin ...

(LBA) where the lineages are grouped basally or artificially at the base of the

phylogenetic tree A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...

without being related. These analyzes instead suggest that DPANN belongs to

Euryarchaeota Euryarchaeota (from Ancient Greek ''εὐρύς'' eurús, "broad, wide") is a phylum of archaea. Euryarchaeota are highly diverse and include methanogens, which produce methane and are often found in intestines, halobacteria, which survive extr ...

or is

polyphyletic A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of conver ...

occupying various positions within Euryarchaeota. The DPANN groups together different phyla with a variety of environmental distribution and metabolism, ranging from symbiotic and

thermophilic A thermophile is an organism—a type of extremophile—that thrives at relatively high temperatures, between . Many thermophiles are archaea, though they can be bacteria or fungi. Thermophilic eubacteria are suggested to have been among the earl ...

forms such as

, acidophiles like

and non-extremophiles like Aenigmarchaeota and Diapherotrites. DPANN was also detected in nitrate-rich groundwater, on the water surface but not below, indicating that these taxa are still quite difficult to locate.

Characteristics

They are characterized by being small in size compared to other

archaea Archaea ( ; singular archaeon ) is a domain of single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially classified as bacteria, receiving the name archaebacteria (in the Archaeba ...

(nanometric size) and in keeping with their small

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ...

, they have limited but sufficient catabolic capacities to lead a free life, although many are episymbionts that depend on a

symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or para ...

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 Biosynthesis is a multi-step, enzyme-Catalysis, catalyzed process where substrate (chemistry), substrates are converted into more complex Product (chemistry), products in living organisms. In biosynthesis, simple Chemical compound, compounds are mo ...

pathways for

nucleotides Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules with ...

aminoacids Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...

, and

lipids Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids in ...

; hence most DPANN archaea, such as ARMAN archaea, which rely on other

microbes A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...

to meet their biological requirements. But those that have the potential to live freely are fermentative and

aerobic Aerobic means "requiring air," in which "air" usually means oxygen. Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics, a form of aerobic exercise * Aerobic respiration, the aerobic process of cel ...

heterotrophs. They are mostly anaerobic and cannot be 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 Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sa ...

. They are rarely found on the ground or in the open ocean.

Classification

* Diapherotrites. Found by phylogenetic analysis of the genomes recovered from the groundwater filtration of a gold mine abandoned in the USA. *

and Micrarchaeota. Discovered in 2006 in acidic mine drainage from a US mine. They are of very small size and provisionally called

ARMAN Arman (November 17, 1928 – October 22, 2005) was a French-born American artist. Born Armand Fernandez in Nice, France, Arman was a painter who moved from using objects for the ink or paint traces they leave (''cachets'', ''allures d'objet'') to ...

(Archaeal Richmond Mine acidophilic nanoorganisms). * Woesearchaeota and Pacearchaeota. They have been identified both in sediments and in surface waters of aquifers and lakes, abounding especially in saline conditions. * Aenigmarchaeota. Found in wastewater from mines and in sediments from hot springs. * Nanohalarchaeota. Distributed in environments with high salinity. *

. 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

Taxonomy

The currently accepted taxonomy is based on the

List of Prokaryotic names with Standing in Nomenclature List of Prokaryotic names with Standing in Nomenclature (LPSN) is an online database that maintains information on the nomenclature, naming and Taxonomy (biology), taxonomy of prokaryotes, following the taxonomy requirements and rulings of the In ...

(LPSN) and

National Center for Biotechnology Information The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. Th ...

(NCBI). Super Phylum "DPANN" Rinke et al. 2013 * Phylum Altarchaeota Probst et al. 2018 (SM1) ** Class "Altarchaeia" corrig. Probst et al. 2014 *** Order "Altarchaeales" corrig. Probst et al. 2014 * Phylum "Iainarchaeota" Diapherotrites"_Rinke_et_al._2013.html" ;"title=" Diapherotrites" Rinke et al. 2013"> Diapherotrites" Rinke et al. 2013(DUSEL-3) ** Class "Iainarchaeia" Rinke et al. 2020 *** "''Candidatus'' Forterrea" Probst & Banfield 2017 *** Order "Iainarchaeales" Rinke et al. 2020 * Phylum " Micrarchaeota" Baker & Dick 2013 ** Class "Micrarchaeia" Vazquez-Campos et al. 2021 *** Order "Anstonellales" Vazquez-Campos et al. 2021 (LFWA-IIIc) *** Order "Burarchaeales" Vazquez-Campos et al. 2021 (LFWA-IIIb) *** Order "Fermentimicrarchaeales" Kadnikov et al. 2020 *** Order "Gugararchaeales" Vazquez-Campos et al. 2021 (LFWA-IIIa) *** Order "Micrarchaeales" Vazquez-Campos et al. 2021 *** Order "Norongarragalinales" Vazquez-Campos et al. 2021 (LFWA-II) * Phylum " Undinarchaeota" Dombrowski et al. 2020 ** Class "Undinarchaeia" Dombrowski et al. 2020 *** Order "Undinarchaeales" Dombrowski et al. 2020 * Phylum " Huberarchaeota" Probst et al. 2019 ** Class "Huberarchaeia" corrig. Probst et al. 2019 *** Order "Huberarchaeales" Rinke et al. 2020 * Phylum " Aenigmatarchaeota" corrig. Rinke et al. 2013 (DSEG, DUSEL2) ** Class "Aenigmatarchaeia" corrig. Rinke et al. 2020 *** Order "Aenigmatarchaeales" corrig. Rinke et al. 2020 * Phylum " Nanohalarchaeota" corrig. Rinke et al. 2013 ** Class "Nanohalobiia" corrig.La Cono et al. 2020 *** Order "Nanohalobiales" La Cono et al. 2020 ** Class ?" Nanohalarchaeia" corrig. Narasingarao et al. 2012 *** Order "Nanohalarchaeales" * Phylum "

" Huber et al. 2002 ** Class "Nanoarchaeia" Vazquez-Campos et al. 2021 *** Order "

Nanoarchaeales Nanoarchaeota (Greek, "dwarf or tiny ancient one") are a phylum (biology), phylum of the Archaea. This phylum currently has only one representative, ''Nanoarchaeum equitans''. Taxonomy 53 marker proteins based Genome Taxonomy Database, GTDB 07-R ...

" Huber et al. 2011 *** Order " Pacearchaeales" (DHVE-5, DUSEL-1) *** Order " Parvarchaeales" Rinke et al. 2020 (ARMAN 4 & 5) *** Order "Tiddalikarchaeales" Vazquez-Campos et al. 2021 (LFW-252_1) *** Order " Woesearchaeales" (DHVE-6) * Phylum ?" Mamarchaeota" * Order ?" Wiannamattarchaeales"

References

External links