Chloroflexia
Scientific classification
Domain:	Bacteria
Kingdom:	Bacillati
Phylum:	Chloroflexota
Class:	Chloroflexia corrig. Gupta et al. 2013
Orders
Chloroflexales Herpetosiphonales Kallotenuales "Thermobaculales"
Synonyms
"Chloroflexia"Castenholz 2001 "Chlorobacteria"Cavalier-Smith 2002 "Chloroflexi"Gupta et al. 2013

TheChloroflexia are a class ofbacteria in thephylumChloroflexota. Chloroflexia are typically filamentous, and can move about throughbacterial gliding. It is named after the orderChloroflexales.^[1]

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 Greekchloros (χλωρός)^[2] meaning "greenish-yellow" and the Latinflexus (offlecto)^[3] meaning "bent" to mean "a green bending".^[4] The name is not due to chlorine, an element confirmed as such in 1810 bySir Humphry Davy and named after its pale green colour.

The Chloroflexia class is a group of deep branchingphotosynthetic bacteria (with the exception ofHerpetosiphon andKallotenue species) that currently consist of three orders:Chloroflexales,Herpetosiphonales, andKallotenuales.^{[1][5][6][7][8]} The Herpetosiphonales and Kallotenuales each consist of a single genus within its own family,Herpetosiphonaceae (Herpetosiphon) andKallotenuaceae (Kallotenue), respectively, whereas theChloroflexales are more phylogenetically diverse.^[1][5][7]

Members of the phylumChloroflexota aremonoderms and stain mostly Gram negative, whereas most bacteria species arediderms and stainGram negative, with the Gram positive exceptions of theBacillota (low GC Gram positives),Actinomycetota (high GC, Gram positives), and theDeinococcota (Gram positive, diderms with thick peptidoglycan).^[9][10][11]

Comparative genomic analysis has recently refined the taxonomy of the classChloroflexia, dividing theChloroflexales into the suborderChloroflexineae consisting of the familiesOscillachloridaceae andChloroflexaceae, and the suborderRoseiflexineae containing familyRoseiflexaceae.^[1] The revised taxonomy was based on the identification of a number ofconserved signature indels (CSIs) which serve as highly reliable molecular markers of shared ancestry.^{[12][13][14][15]}

Additional support for the division of the Chloroflexales into two suborders is the observed differences in physiological characteristics where each suborder is characterized by distinctcarotenoids,quinones, andfatty acid profiles that are consistently absent in the other suborder.^[1][16][17]

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 inphotosynthetic organisms, has been found exclusively among all members in the genusChloroflexus, and is thought to play an important functional role.^[18][19]

Additional work has been done using CSIs to demarcate the phylogenetic position of Chloroflexia relative to other photosynthetic groups such as the Cyanobacteria.^[20] Chloroflexia shares a number of CSIs withChlorobiota in the chlorophyll-synthesizing proteins. As the two lineages are not otherwise closely related, the interpretation is that the CSIs are the result of ahorizontal gene transfer event between the two. Chloroflexia in turn acquired these proteins by another HGT from a "Clade C" marine cyanobacteria.^[21]

The currently accepted taxonomy is as follows:^[1][5][28]

Class ChloroflexiaGupta et al. 2013

• Genus ?"CandidatusChlorohelix"Tsuji et al. 2024
• Genus ?"Dehalobium"Wu et al. 2002^[29]
• Genus ?"CandidatusLithoflexus"Saghai et al. 2020
• Genus ?"CandidatusSarcinithrix"Nierychlo et al. 2019
• Order "Thermobaculales"Chuvochina et al. 2023
  • Family "Thermobaculaceae"Chuvochina et al. 2023
    • Genus "Thermobaculum"Botero et al. 2004
• Order Kallotenuales]Cole et al. 2013
  • Family KallotenuaceaeCole et al. 2013
    • GenusKallotenueCole et al. 2013
• OrderHerpetosiphonalesGupta et al. 2013
  • FamilyHerpetosiphonaceaeGupta et al. 2013
    • Genus "CandidatusAnthektikosiphon"Ward, Fischer & McGlynn 2020
    • GenusHerpetosiphonHolt & Lewin 1968
• OrderChloroflexalesGupta et al. 2013
  • SuborderRoseiflexineaeGupta et al. 2013
    • Family RoseiflexaceaeGupta et al. 2013 ["Kouleotrichaceae"Mehrshad et al. 2018]
      • Genus ?HeliothrixPierson et al. 1986
      • Genus "Kouleothrix"Kohno et al. 2002
      • Genus "CandidatusRibeiella"Petriglieri et al. 2023
      • GenusRoseiflexusHanada et al. 2002
  • SuborderChloroflexineaeGupta et al. 2013
    • Family ChloroflexaceaeGupta et al. 2013
      • Genus ?"CandidatusChloranaerofilum"Thiel et al. 2016
      • GenusChloroflexusPierson & Castenholz 1974 ["Chlorocrinis"Ward et al. 1998]
    • Family OscillochloridaceaeGupta et al. 2013
      • Genus ?Chloronema ♪Dubinina & Gorlenko 1975
      • Genus "CandidatusChloroploca"Gorlenko et al. 2014
      • GenusOscillochlorisGorlenko & Pivovarova 1989
      • Genus "CandidatusViridilinea"Grouzdev et al. 2018

• List of bacteria genera
• List of bacterial orders
• Green sulfur bacteria

• Garrity GM, Holt JG (2001)."Phylum BVI. Chloroflexi phy. nov". In Boone, D.R., Castenholz, R.W. (eds.).The Archaea and the deeply branching and phototrophic Bacteria. Bergey's Manual of Systematic Bacteriology. Vol. 1 (2nd ed.). New York: Springer Verlag. p. 169.ISBN 978-0-387-98771-2.

Wikispecies has information related toChloroflexia.

• Phototrophic bacteria

• Articles containing Ancient Greek (to 1453)-language text
• Articles with short description
• Short description is different from Wikidata
• Articles with 'species' microformats