Pelagibacterales

"Pelagibacterales"
Microscopy image of SAR11
Scientific classification
Domain:
Bacteria
Phylum:
Pseudomonadota
Class:
Alphaproteobacteria
Subclass:
Rickettsidae
Order:
"Pelagibacterales"

Grote et al. 2012[1]
Families
Synonyms[1]
  • SAR11 Clade

The Pelagibacterales are an order in the Alphaproteobacteria composed of free-living marine bacteria that make up roughly one in three cells at the ocean's surface.[2][3][4] Overall, members of the Pelagibacterales are estimated to make up between a quarter and a half of all prokaryotic cells in the ocean.[5]

Initially, this taxon was known solely by metagenomic data and was known as the SAR11 clade. It was first placed in the Rickettsiales, but was later raised to the rank of order, and then placed as sister order to the Rickettsiales in the subclass Rickettsidae.[4] It includes the highly abundant marine species Pelagibacter ubique.

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 oligotrophs (scavengers) and feed on dissolved organic carbon and nitrogen.[3] They are unable to fix carbon or nitrogen, but can perform the TCA cycle with glyoxylate bypass and are able to synthesise all amino acids except glycine,[7] as well as some cofactors.[8] They also have an unusual and unexpected requirement for reduced sulfur.[9]

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 Acaryochloris marina, P. ubique is not photosynthetic — specifically, it does not use light to increase the bond energy of an electron pair — but it does possess proteorhodopsin (including retinol biosynthesis) for ATP production from light.[11]

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]

  1. ^ a b Grote J, Thrash JC, Huggett MJ, Landry ZC, Carini P, Giovannoni SJ, Rappe MS (2012). "Streamlining and core genome conservation among highly divergent members of the SAR11 clade". mBio. 3 (5): 1–13. doi:10.1128/mBio.00252-12. PMC 3448164. PMID 22991429.
  2. ^ J. Cameron Thrash; Alex Boyd; Megan J. Huggett; Jana Grote; Paul Carini; Ryan J. Yoder; Barbara Robbertse; Joseph W. Spatafora; Michael S. Rappé; Stephen J. Giovannoni (June 2011). "Phylogenomic evidence for a common ancestor of mitochondria and the SAR11 clade". Scientific Reports. 1: 13. Bibcode:2011NatSR...1E..13T. doi:10.1038/srep00013. PMC 3216501. PMID 22355532.
  3. ^ a b Morris RM, Rappé MS, Connon SA, et al. (2002). "SAR11 clade dominates ocean surface bacterioplankton communities". Nature. 420 (6917): 806–10. Bibcode:2002Natur.420..806M. doi:10.1038/nature01240. PMID 12490947. S2CID 4360530.
  4. ^ a b Cite error: The named reference Ferla2013 was invoked but never defined (see the help page).
  5. ^ a b Giovannoni, Stephen J. (2017-01-03). "SAR11 Bacteria: The Most Abundant Plankton in the Oceans". Annual Review of Marine Science. 9: 231–255. Bibcode:2017ARMS....9..231G. doi:10.1146/annurev-marine-010814-015934. ISSN 1941-0611. PMID 27687974.
  6. ^ Rappé MS, Connon SA, Vergin KL, Giovannoni SJ (August 2002). "Cultivation of the ubiquitous SAR11 marine bacterioplankton clade". Nature. 418 (6898): 630–3. Bibcode:2002Natur.418..630R. doi:10.1038/nature00917. PMID 12167859. S2CID 4352877.
  7. ^ H. James Tripp; Michael S. Schwalbach; Michelle M. Meyer; Joshua B. Kitner; Ronald R. Breaker & Stephen J. Giovannoni (January 2009). "Unique glycine-activated riboswitch linked to glycine-serine auxotrophy in SAR11". Environmental Microbiology. 11 (1): 230–8. doi:10.1111/j.1462-2920.2008.01758.x. PMC 2621071. PMID 19125817.
  8. ^ Giovannoni, S. J.; Tripp, H. J.; Givan, S.; Podar, M.; Vergin, K. L.; Baptista, D.; Bibbs, L.; Eads, J.; Richardson, T. H.; Noordewier, M.; Rappé, M. S.; Short, J. M.; Carrington, J. C.; Mathur, E. J. (2005). "Genome Streamlining in a Cosmopolitan Oceanic Bacterium". Science. 309 (5738): 1242–1245. Bibcode:2005Sci...309.1242G. doi:10.1126/science.1114057. PMID 16109880. S2CID 16221415.
  9. ^ H. James Tripp; Joshua B. Kitner; Michael S. Schwalbach; John W. H. Dacey; Larry J. Wilhelm & Stephen J. Giovannoni (April 2008). "SAR11 marine bacteria require exogenous reduced sulfur for growth". Nature. 452 (7188): 741–4. Bibcode:2008Natur.452..741T. doi:10.1038/nature06776. PMID 18337719. S2CID 205212536.
  10. ^ Schwalbach, M. S.; Tripp, H. J.; Steindler, L.; Smith, D. P.; Giovannoni, S. J. (2010). "The presence of the glycolysis operon in SAR11 genomes is positively correlated with ocean productivity". Environmental Microbiology. 12 (2): 490–500. doi:10.1111/j.1462-2920.2009.02092.x. PMID 19889000.
  11. ^ Giovannoni, S. J.; Bibbs, L.; Cho, J. C.; Stapels, M. D.; Desiderio, R.; Vergin, K. L.; Rappé, M. S.; Laney, S.; Wilhelm, L. J.; Tripp, H. J.; Mathur, E. J.; Barofsky, D. F. (2005). "Proteorhodopsin in the ubiquitous marine bacterium SAR11". Nature. 438 (7064): 82–85. Bibcode:2005Natur.438...82G. doi:10.1038/nature04032. PMID 16267553. S2CID 4414677.
  12. ^ Carini, P.; White, A. E.; Campbell, E. O.; Giovannoni, S. J. (2014). "Methane production by phosphate-starved SAR11 chemoheterotrophic marine bacteria". Nature Communications. 5: 4346. Bibcode:2014NatCo...5.4346C. doi:10.1038/ncomms5346. PMID 25000228.
  13. ^ Don J. Brenner; Noel R. Krieg; James T. Staley (July 26, 2005) [1984(Williams & Wilkins)]. George M. Garrity (ed.). The Proteobacteria. Bergey's Manual of Systematic Bacteriology. Vol. 2C (2nd ed.). New York: Springer. pp. 1388. ISBN 978-0-387-24145-6. British Library no. GBA561951.