Pelagibacterales
| "Pelagibacterales" | |
|---|---|
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| Microscopy image of SAR11 | |
| Scientific classification | |
| Domain: | |
| Phylum: | |
| Class: | |
| Subclass: | Rickettsidae |
| Order: | "Pelagibacterales" Grote et al. 2012[1]
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| Families | |
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| Synonyms[1] | |
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The Pelagibacterales are an order in the
Initially, this taxon was known solely by
Bacteria in this order are unusually small.[6] Due to their small genome size and limited metabolic function, Pelagibacterales have become a model organism for 'streamlining theory'.[5]
P. ubique and related species are
P. ubique and members of the oceanic subgroup I possess gluconeogenesis, but not a typical glycolysis pathway, whereas other subgroups are capable of typical glycolysis.[10]
Unlike
SAR11 bacteria are responsible for much of the dissolved methane in the ocean surface. They extract phosphate from methylphosphonic acid.[12]
Although the taxon derives its name from the type species P. ubique (status Candidatus species), this species has not yet been validly published, and therefore neither the order name nor the species name has official taxonomic standing.[13]
Subgroups
Currently, the order is divided into five subgroups:[14]
- Subgroup Ia, open ocean, crown group — includes P. ubique HTCC1062
- Subgroup Ib, open ocean, sister clade to Ia
- Subgroup II, coastal, basal to Ia + Ib
- Subgroup III, brackish, basal to I + II along with its sister clade IV
- Subgroup IV, also known as the LD12 clade, freshwater[15]
- Subgroup V, which includes alphaproteobacterium HIMB59, basal to the remainder
The above results in a cladogram of the Pelagibacterales as follows:
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Subgroup V (includes α-proteobacterium HIMB59) | |||||||||||||||||||||||||||||||
Phylogenetic placement and endosymbiotic theory
A 2011 study by researchers of the University of Hawaiʻi at Mānoa and Oregon State University, indicated that SAR11 could be the ancestor of mitochondria in most eukaryotic cells.[2] However, this result could represent a tree reconstruction artifact due to compositional bias.[16]
| Schematic ribosomal RNA phylogeny of Alphaproteobacteria | ||||||||||||||||||||||||
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| The cladogram of Rickettsidae has been inferred by Ferla et al. [4] from the comparison of 16S + 23S ribosomal RNA sequences. |
References
- ^ PMID 22991429.
- ^ PMID 22355532.
- ^ S2CID 4360530.
- ^ PMID 24349502.
- ^ PMID 27687974.
- S2CID 4352877.
- PMID 19125817.
- S2CID 16221415.
- S2CID 205212536.
- PMID 19889000.
- S2CID 4414677.
- PMID 25000228.
- ISBN 978-0-387-24145-6. British Library no. GBA561951.
- ^ Robert M. Morris, K.L.V., Jang-Cheon Cho, Michael S. Rappé, Craig A. Carlson, Stephen J. Giovannoni, Temporal and Spatial Response of Bacterioplankton Lineages to Annual Convective Overturn at the Bermuda Atlantic Time-Series Study Site" Limnology and Oceanography 50(5) p. 1687-1696.
- ^ Salcher, M.M., J. Pernthaler, and T. Posch, Seasonal bloom dynamics and ecophysiology of the freshwater sister clade of SAR11 bacteria 'that rule the waves' (LD12). ISME J, 2011.
- PMID 22291975.
