Nomurabacteria is a

candidate A candidate, or nominee, is the prospective recipient of an award or honor, or a person seeking or being considered for some kind of position; for example: * to be elected to an office — in this case a candidate selection procedure occurs. * t ...

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 f ...

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

belonging to the

CPR group The candidate phyla radiation (also referred to as CPR group) is a large evolutionary radiation of bacterial lineages whose members are mostly uncultivated and only known from metagenomics and single cell sequencing. They have been described as na ...

so they are ultra-small bacteria. They have been found in a wide variety of environments, mainly in

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, sand a ...

under anaerobic conditions.Castelle, C., Brown, C., Thomas, B. et al
Unusual respiratory capacity and nitrogen metabolism in a Parcubacterium (OD1) of the Candidate Phyla Radiation.
Sci Rep 7, 40101 (2017) doi:10.1038/srep40101Hug, L. A. et al. 2016
A new view of the tree of life
Nature Microbiology, 1, 16048. Bacteria of this phylum share several of their characteristics with other ultra-small bacteria: such as nanometric size, small genomes, reduced

metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

, low capacity to synthesize nucleotides and

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 ami ...

, they lack respiratory chains and the Krebs cycle. In addition, many can be

endosymbionts An ''endosymbiont'' or ''endobiont'' is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship. (The term endosymbiosis is from the Greek: ἔνδον ''endon'' "within" ...

of larger bacteria.Rijja Hussain Bokhari, Nooreen Amirjan, Hyeonsoo Jeong, Kyung Mo Kim, Gustavo Caetano-Anollés, Arshan Nasir (2020)
Bacterial Origin and Reductive Evolution of the CPR Group
Oxford Academic. https://doi.org/10.1093/gbe/evaa024 Phylogenetic analyzes have suggested that Nomurabacteria and the other ultra-small bacteria make up the most basal clade of all bacteria. The

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 Archaebac ...

of the DPANN group are ultra-small archaea that share the same characteristics with these bacteria and are the most basal group of the archaeo-eukaryotic clade, although it can also be

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

eukaryotes Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...

and the other archaea as will be seen below. In some phylogenetic analyzes of the proteome, ultra-small bacteria emerge outside the traditional bacterial domain and emerge as a paraphyletic group of traditional Bacteria and the clade composed of archaea and eukaryotes. In these analyzes Nomurabacteria turns out to be the most

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

of all cellular organisms.

Phylogeny

Proteome analyzes have shown that Nomurabacteria can be the most basal clade of cellular organisms and that the other CPR bacteria are a

group as can be seen in the cladogram that shows the phylogenetic relationships between multiple bacterial, archaean and eukaryotes. A Novel Representation Of The Tree Of Life

A Novel Representation Of The Tree Of Life

References

{{Taxonbar, from=Q99238832 Bacteria Candidatus taxa