Ultramicrobacteria
Ultramicrobacteria are
Microbacterial studies from Berkeley Labs at UC Berkeley have produced detailed microscopy images of ultra-small microbial species.[6] Cells imaged have an average volume of 0.009 μm3, meaning that about 150,000 of them could fit on the tip of a human hair.[6] These bacteria were found in groundwater samples and analyzed with 2-D and 3-D cryogenic transmission electron microscopy. These ultra-small bacteria, about 1 million base pairs long,[6] display dense spirals of DNA, few ribosomes, hair-like fibrous appendages, and minimized metabolic systems.[6] Such cells probably gain most essential nutrients and metabolites from other bacteria.[6] Bacteria in the ultra-small size range are thought to be rather common but difficult to detect. [6]
Ultramicrobacteria are commonly confused with ultramicrocells, the latter of which are the dormant, stress-resistant forms of larger cells that form under starvation conditions[1][2][7] (i.e. these larger cells downregulate their metabolism, stop growing and stabilize their DNA to create ultramicrocells that remain viable for years[1][8]) whereas the small size of ultramicrobacteria is not a starvation response and is consistent even under nutrient-rich conditions.[3]
The term "nanobacteria" is sometimes used synonymously with ultramicrobacteria in the scientific literature,[2] but ultramicrobacteria are distinct from the purported nanobacteria or "calcifying nanoparticles", which were proposed to be living organisms that were 0.1 μm in diameter.[9] These structures are now thought to be nonliving,[10] and likely precipitated particles of inorganic material.[11][12]
See also
- L-form bacteria
- Mycoplasma – smallest known bacteria (300 nm)
- Nanoarchaeum– smallest known archaeum (400 nm)
- Nanobacteria– possible lifeforms smaller than bacteria (<200 nm)
- Nanobe – possible smallest lifeforms (20 nm)
- Pithovirus – largest known virus (1,500 nm)
- Pandoravirus – one of the largest known viruses (1,000 nm)
- Parvovirus– smallest known viruses (18–28 nm)
- Prion – smallest known infectious agent (≈10 nm)
- ND5 and MY14T – two aerobic, Gram-negative, rod-shaped bacteria[13]
References
- ^ ISBN 9780470015902. Retrieved September 26, 2017.
- ^ S2CID 6391715.
- ^ PMID 9097435.
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- PMID 12501296.
- ^ a b c d e f Krotz, D. (2015). "First Detailed Microscopy Evidence of Bacteria at the Lower Size Limit of Life". Retrieved 2020-05-11.
- .
- PMID 8561477.
- PMID 17530922.
- S2CID 20169194.
- PMID 18282102.
- PMID 18385376.
- PMID 20370834.
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