Английская Википедия:Hydrobacteria
Шаблон:Short description Шаблон:Automatic taxobox
Hydrobacteria is a taxon containing approximately one-third of prokaryote species, mostly gram-negative bacteria and their relatives.[1] It was found to be the closest relative of an even larger group of Bacteria, Terrabacteria, which are mostly gram positive bacteria.[2][1] The name Hydrobacteria (hydro = "water") refers to the moist environment inferred for the common ancestor of those species. In contrast, species of Terrabacteria possess adaptations for life on land.[2][1]
The content of Hydrobacteria has grown to include these superphyla and phyla: Acidobacteriota, Aquificota, Bdellovibrionota, Campylobacterota, Deferribacterota, Dependentiae, Desulfobacterota, Desulfuromonadota, Elusimicrobiota, FCB superphylum, Myxococcota, Nitrospirota, Proteobacteria, PVC superphylum, and Spirochaetota.[3][4]
Some unrooted molecular phylogenetic analyses[5][6] have not supported this dichotomy of Terrabacteria and Hydrobacteria, but the most recent genomic analyses,[3][4] including those that have focused on rooting the tree,[3] have found these two groups to be monophyletic.
Hydrobacteria and Terrabacteria were inferred to have diverged approximately 3 billion years ago, suggesting that land (continents) had been colonized by prokaryotes at that time.[1] Together, Hydrobacteria and Terrabacteria form a large group containing 97% of prokaryotes and 99% of all species of Bacteria known by 2009, and placed in the taxon Selabacteria, in allusion to their phototrophic abilities (selas = light).[7] Currently, the bacterial phyla that are outside of Hydrobacteria + Terrabacteria, and thus justifying the taxon Selabacteria, are debated and may or may not include Fusobacteria.[3][4]
"Gracilicutes," which was described in 1978 by Gibbons and Murray,[8] is sometimes used in place of Hydrobacteria. However, "Gracilicutes" included cyanobacteria (a member of Terrabacteria) and was not constructed under the now generally accepted three-domain system.[8] More recently, a redefinition of "Gracilicutes" was proposed[9] but it did not include a molecular phylogeny or statistical analyses. Also, it did not follow the three-domain system, claiming instead that the lineage of eukaryotes + Archaea is nested within Bacteria as a close relative of Actinomycetota, a tree not supported in any molecular phylogeny.
Phylogeny
The definition of two major divisions within the domain Bacteria, Hydrobacteria and Terrabacteria, has come largely from rooted phylogenetic analyses of genomes.[2][1][3][4] Unrooted analyses have not fully supported this division,[6][5] drawing attention to the importance of rooted trees of life.
The two recent analyses of bacterial phylogeny both supported the division of Hydrobacteria and Terrabacteria.[3][4] However, they interpreted the evolution of the cell wall differently, with one concluding that the last common ancestor of Bacteria was a monoderm (gram-positive bacteria[3]) and the other concluding that it was a diderm (gram-negative bacteria[4]). The following tree is redrawn from one of those two recent studies,[3] showing the phylogeny of bacterial phyla and superphyla, with the position of Fusobacteria being unresolved and DST being the closest relative of Terrabacteria:
References
Шаблон:Bacteria classification Шаблон:Bacteria Шаблон:Taxonbar Шаблон:Authority Control
- ↑ 1,0 1,1 1,2 1,3 1,4 Шаблон:Cite journal
- ↑ 2,0 2,1 2,2 Шаблон:Cite journal
- ↑ 3,0 3,1 3,2 3,3 3,4 3,5 3,6 3,7 Шаблон:Cite journal
- ↑ 4,0 4,1 4,2 4,3 4,4 4,5 Шаблон:Cite journal
- ↑ 5,0 5,1 Шаблон:Cite journal
- ↑ 6,0 6,1 Шаблон:Cite journal
- ↑ Шаблон:Cite book
- ↑ 8,0 8,1 Шаблон:Cite journal
- ↑ Шаблон:Cite journal
