Bacteria
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This article is about the microorganisms. For the genus, see Bacterium (genus). For other uses, see Bacteria (disambiguation).
Bacteria
Temporal range: Archean or earlier – Recent
Had'n
Archean
Proterozoic
Pha.
Scanning electron micrograph of Escherichia coli bacilli
Scientific classification
Domain:
Bacteria
Woese et al., 1990[1]
Phyla[2]
Gram positive / no outer membrane
Actinobacteria (high-G+C)
Firmicutes (low-G+C)
Tenericutes (no wall)
Gram negative / outer membrane present
Aquificae
Bacteroidetes/Fibrobacteres–Chlorobi (FCB group)
Deinococcus-Thermus
Fusobacteria
Gemmatimonadetes
Nitrospirae
Planctomycetes–Verrucomicrobia/Chlamydiae (PVC group)
Proteobacteria
Spirochaetes
Synergistetes
Unknown / ungrouped
Acidobacteria
Chloroflexi
Chrysiogenetes
Cyanobacteria
Deferribacteres
Dictyoglomi
Thermodesulfobacteria
Thermotogae
Synonyms
Eubacteria Woese & Fox, 1977[3]
Bacteria (i/bækˈtɪəriə/; singular: bacterium) constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals. Bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste,[4] and the deep portions of Earth's crust. Bacteria also live in symbiotic and parasitic relationships with plants and animals. They are also known to have flourished in manned spacecraft.[5]
There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water. There are approximately 5×1030 bacteria on Earth,[6] forming a biomass which exceeds that of all plants and animals.[7]...