Nomurabacteria is a

candidate A candidate, or nominee, is a prospective recipient of an award or honor, or a person seeking or being considered for some kind of position. For example, one can be a candidate for membership in a group (sociology), group or election to an offic ...

phylum In biology, a phylum (; : phyla) is a level of classification, or taxonomic rank, that is below Kingdom (biology), kingdom and above Class (biology), class. Traditionally, in botany the term division (taxonomy), division has been used instead ...

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

belonging to the CPR group. They are ultra-small bacteria that have been found in a wide variety of environments, mainly in

sediments Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...

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, nanometric size, small genomes, reduced

metabolism Metabolism (, from ''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 cellular processes; the co ...

, and low capacity to synthesize

nucleotides Nucleotides are Organic compound, organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both o ...

and aminoacids. They also lack respiratory chains and the

Krebs cycle The citric acid cycle—also known as the Krebs cycle, Szent–Györgyi–Krebs cycle, or TCA cycle (tricarboxylic acid cycle)—is a series of biochemical reactions that release the energy stored in nutrients through acetyl-CoA oxidation. The e ...

. In addition, many can be

endosymbionts An endosymbiont or endobiont is an organism that lives within the body or cells of another organism. Typically the two organisms are in a mutualistic relationship. Examples are nitrogen-fixing bacteria (called rhizobia), which live in the root ...

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 ( ) is a Domain (biology), domain of organisms. Traditionally, Archaea only included its Prokaryote, prokaryotic members, but this has since been found to be paraphyletic, as eukaryotes are known to have evolved from archaea. Even thou ...

of the

Nanobdellati Nanobdellati ( syn. "DPANN") is a kingdom of archaea first proposed in 2013. Many members show novel signs of horizontal gene transfer from other domains of life. They are known as nanoarchaea or ultra-small archaea due to their smaller size (na ...

kingdom 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 Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

eukaryotes The eukaryotes ( ) constitute the domain of Eukaryota or Eukarya, organisms whose cells have a membrane-bound nucleus. All animals, plants, fungi, seaweeds, and many unicellular organisms are eukaryotes. They constitute a major group of ...

and the other archaea as will be seen below. In some phylogenetic analyzes of the

proteome A proteome is the entire set of proteins that is, or can be, expressed by a genome, cell, tissue, or organism at a certain time. It is the set of expressed proteins in a given type of cell or organism, at a given time, under defined conditions. P ...

, ultra-small bacteria emerge outside the traditional bacterial domain and instead 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

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

of all cellular organisms.

Phylogeny

Proteome A proteome is the entire set of proteins that is, or can be, expressed by a genome, cell, tissue, or organism at a certain time. It is the set of expressed proteins in a given type of cell or organism, at a given time, under defined conditions. P ...

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 A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

that shows the phylogenetic relationships between multiple bacterial, archaean and eukaryotes. A Novel Representation Of The Tree Of Life

References

{{Taxonbar, from=Q99238832 Bacteria Candidatus taxa