Chloroflexia Explained

The Chloroflexia are a class of bacteria in the phylum Chloroflexota. Chloroflexia are typically filamentous, and can move about through bacterial gliding. It is named after the order Chloroflexales.

Etymology

The name "Chloroflexi" is a Neolatin plural of "Chloroflexus", which is the name of the first genus described. The noun is a combination of the Greek chloros (χλωρός) meaning "greenish-yellow" and the Latin flexus (of flecto)[1] meaning "bent" to mean "a green bending".[2] The name is not due to chlorine, an element confirmed as such in 1810 by Sir Humphry Davy and named after its pale green colour.

Taxonomy and molecular signatures

See also: Genomics and Conserved signature indels. The Chloroflexia class is a group of deep branching photosynthetic bacteria (with the exception of Herpetosiphon and Kallotenue species) that currently consist of three orders: Chloroflexales, Herpetosiphonales, and Kallotenuales.[3] [4] [5] [6] [7] The Herpetosiphonales and Kallotenuales each consist of a single genus within its own family, Herpetosiphonaceae (Herpetosiphon) and Kallotenuaceae (Kallotenue), respectively, whereas the Chloroflexales are more phylogenetically diverse.[3] [4] [6]

Microscopic distinguishing characteristics

Members of the phylum Chloroflexota are monoderms and stain mostly Gram negative, whereas most bacteria species are diderms and stain Gram negative, with the Gram positive exceptions of the Bacillota (low GC Gram positives), Actinomycetota (high GC, Gram positives), and the Deinococcota (Gram positive, diderms with thick peptidoglycan).[8] [9] [10]

Genetic distinguishing characteristics

Comparative genomic analysis has recently refined the taxonomy of the class Chloroflexia, dividing the Chloroflexales into the suborder Chloroflexineae consisting of the families Oscillachloridaceae and Chloroflexaceae, and the suborder Roseiflexineae containing family Roseiflexaceae.[3] The revised taxonomy was based on the identification of a number of conserved signature indels (CSIs) which serve as highly reliable molecular markers of shared ancestry.[11] [12] [13] [14]

Physiological distinguishing characteristics

Additional support for the division of the Chloroflexales into two suborders is the observed differences in physiological characteristics where each suborder is characterized by distinct carotenoids, quinones, and fatty acid profiles that are consistently absent in the other suborder.[3] [15] [16]

In addition to demarcating taxonomic ranks, CSIs may play a role in the unique characteristics of members within the clade: In particular, a four-amino-acid insert in the protein pyruvate flavodoxin/ferredoxin oxidoreductase, a protein which plays important roles in photosynthetic organisms, has been found exclusively among all members in the genus Chloroflexus, and is thought to play an important functional role.[17] [18]

Additional work has been done using CSIs to demarcate the phylogenetic position of Chloroflexia relative to other photosynthetic groups such as the Cyanobacteria.[19] Chloroflexia shares a number of CSIs with Chlorobiota in the chlorophyll-synthesizing proteins. As the two lineages are not otherwise closely related, the interpretation is that the CSIs are the result of a horizontal gene transfer event between the two. Chloroflexia in turn acquired these proteins by another HGT from a "Clade C" marine cyanobacteria.[20]

Taxonomy

See also: Bacterial taxonomy. The currently accepted taxonomy is as follows:[3] [4]

Class Chloroflexia Gupta et al. 2013

See also

Further reading

Notes and References

  1. Lewis, Charlton T. and Charles Short, A Latin Dictionary. Oxford: Clarendon Press, 1879. Online version at Perseus
  2. Book: Bergey's Manual of Systematic Bacteriology . 2A . Introductory Essays . George M. . Garrity . Don J. . Brenner . Noel R. . Krieg . James T. Staley . Springer (orig-pub London: Williams & Wilkins) . New York . 2nd . 978-0-387-24143-2 . 304 . July 26, 2005 . 1984 . British Library no. GBA561951.
  3. Gupta RS, Chander P, George S . Phylogenetic framework and molecular signatures for the class Chloroflexia and its different clades; proposal for division of the class Chloroflexia class. nov. [corrected] into the suborder Chloroflexineae subord. nov., consisting of the emended family Oscillochloridaceae and the family Chloroflexaceae fam. nov., and the suborder Roseiflexineae subord. nov., containing the family Roseiflexaceae fam. nov. . Antonie van Leeuwenhoek . 103. 1. 99–119 . 2013. 22903492 . 10.1007/s10482-012-9790-3 .
  4. Cole JK, Gieler BA, Heisler DL, Palisoc MM, Williams AJ, Dohnalkova AC, Ming H, Yu TT, Dodsworth JA, Li WJ, Hedlund BP . Kallotenue papyrolyticum gen. nov., sp. nov., a cellulolytic and filamentous thermophile that represents a novel lineage (Kallotenuales ord. nov., Kallotenuaceae fam. nov.) within the class Chloroflexia . Int. J. Syst. Evol. Microbiol. . 63 . Part 12 . 4675–82 . 2013 . 23950149 . 10.1099/ijs.0.053348-0.
  5. Gupta RS, Mukhtar T, Singh B . Evolutionary relationships among photosynthetic prokaryotes (Heliobacterium chlorum, Chloroflexus aurantiacus, cyanobacteria, Chlorobium tepidum and proteobacteria): Implications regarding the origin of photosynthesis . Mol Microbiol . 32 . 5 . 893–906 . 1999 . 10361294 . 10.1046/j.1365-2958.1999.01417.x.
  6. Web site: Sayers . Chloroflexia . National Center for Biotechnology Information (NCBI) . taxonomy database . 2016-10-25 . dmy-all . etal.
  7. Euzeby J . List of new names and new combinations previously effectively, but not validly, published . Int. J. Syst. Evol. Microbiol. . 63 . 1577–1580 . 2013 . 10.1099/ijs.0.052571-0 . .
  8. Sutcliffe . I.C. . A phylum level perspective on bacterial cell envelope architecture . 10.1016/j.tim.2010.06.005 . Trends in Microbiology . 18 . 10 . 464–470 . 2010 . 20637628.
  9. Campbell C, Sutcliffe IC, Gupta RS . Comparative proteome analysis of Acidaminococcus intestini supports a relationship between outer membrane biogenesis in Negativicutes and Proteobacteria . Arch. Microbiol. . 196 . 4 . 307–310 . 2014 . 24535491 . 10.1007/s00203-014-0964-4 .
  10. Gupta RS . Evolutionary relationships among photosynthetic bacteria . Photosynth Res . 76 . 1–3 . 173–183 . 2003 . 16228576 . 10.1023/A:1024999314839 .
  11. Gupta, R.S. . Impact of genomics on the understanding of microbial evolution and classification: The importance of Darwin's views on classification . FEMS Microbiol. Rev. . 40 . 4 . 520–553 . 2016 . 27279642 . 10.1093/femsre/fuw011 . free .
  12. Gupta . R.S. . Protein phylogenies and signature sequences: A reappraisal of evolutionary relationships among archaebacteria, eubacteria, and eukaryotes . Microbiology and Molecular Biology Reviews . 62 . 4 . 1435–1491 . 1998 . 9841678 . 98952 . 10.1128/MMBR.62.4.1435-1491.1998.
  13. Rokas . A. . Holland . P.W. . Rare genomic changes as a tool for phylogenetics . Trends in Ecology & Evolution . 15 . 11 . 454–459 . 2000 . 11050348 . 10.1016/S0169-5347(00)01967-4.
  14. Gupta . R.S. . Griffiths . E. . Critical issues in bacterial phylogeny . Theoretical Population Biology . 61 . 4 . 423–434 . 2002 . 12167362 . 10.1006/tpbi.2002.1589.
  15. Book: Hanada, S. . Pierson, B.K. . 2006 . The Family Chloroflexaceae . The Prokaryotes: A handbook on the biology of bacteria . 815–842 . Dworkin, M. . Falkow, S. . Rosenberg, E. . Schleifer, K.H. . Stackebrandt, E. . Springer . New York.
  16. Book: Pierson, B.K. . Castenholz, R.W. . 1992 . The Family Chloroflexaceae . The Prokaryotes . 3754–3775 . Balows, A. . Truper, H.G. . Dworkin, M. . Harder, W. . Schleifer, K.H. . Springer . New York.
  17. Gupta RS . Molecular signatures for the main phyla of photosynthetic bacteria and their subgroups . Photosynth. Res. . 104 . 2–3 . 357–372 . 2010 . 20414806 . 10.1007/s11120-010-9553-9.
  18. Stolz . F.M. . Hansmann . I. . An MspI RFLP detected by probe pFMS76 D20S23 isolated from a flow-sorted chromosome 20-specific DNA library . Nucleic Acids Research . 18 . 7 . 1929 . 1990 . 1692410 . 330654 . 10.1093/nar/18.7.1929.
  19. Robert E. Blankenship . Khadka B, Adeolu M, Blankenship RE, Gupta RS . Novel insights into the origin and diversification of photosynthesis based on analyses of conserved indels in the core reaction center proteins . Photosynth Res . 131 . 2 . 159–171 . 2016 . 27638319 . 10.1007/s11120-016-0307-1.
  20. Gupta RS . Origin and spread of photosynthesis based upon conserved sequence features in key bacteriochlorophyll biosynthesis proteins . Mol Biol Evol . 29 . 11 . 3397–412 . 2012 . 22628531 . 10.1093/molbev/mss145 . free .
  21. Web site: The LTP . 20 November 2023.
  22. Web site: LTP_all tree in newick format. 20 November 2023.
  23. Web site: LTP_08_2023 Release Notes. 20 November 2023.
  24. Web site: GTDB release 07-RS207 . Genome Taxonomy Database. 20 June 2022.
  25. Web site: bac120_r207.sp_labels . Genome Taxonomy Database. 20 June 2022.
  26. Web site: Taxon History . Genome Taxonomy Database. 20 June 2022.
  27. Wu . Q. . Watts . J. E. M. . Sowers . K. R. . May . H. D. . Identification of a Bacterium That Specifically Catalyzes the Reductive Dechlorination of Polychlorinated Biphenyls with Doubly Flanked Chlorines . 10.1128/AEM.68.2.807-812.2002 . Applied and Environmental Microbiology . 68 . 2 . 807–812 . 2002 . 11823222. 126686 .

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Chloroflexia".

Except where otherwise indicated, Everything.Explained.Today is © Copyright 2009-2024, A B Cryer, All Rights Reserved. Cookie policy.