Chloroflexi
Encyclopedia
Chloroflexi is one of four classes of bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 in the phylum
Phylum
In biology, a phylum The term was coined by Georges Cuvier from Greek φῦλον phylon, "race, stock," related to φυλή phyle, "tribe, clan." is a taxonomic rank below kingdom and above class. "Phylum" is equivalent to the botanical term division....

 Chloroflexi
Chloroflexi (phylum)
The Chloroflexi or Chlorobacteria are a phylum of bacteria containing isolates with a diversity of phenotypes including members that are aerobic thermophiles, which use oxygen and grow well in high temperatures, anoxygenic phototrophs, which use light for photosynthesis, and anaerobic...

, known as filamentous green non-sulfur bacteria. They produce energy from light and are named for their green pigment, usually found in photosynthetic bodies called chlorosome
Chlorosome
A Chlorosome is a photosynthetic antenna complex found in green sulfur bacteria and some green filamentous anoxygenic phototrophs . They differ from other antenna complexes by their large size and lack of protein matrix supporting the photosynthetic pigments...

s.

Chloroflexi are typically filamentous, and can move about through bacterial gliding
Bacterial gliding
Bacterial gliding is a process whereby a bacterium can move under its own power. This process does not involve the use of flagella, which is a more common means of motility in bacteria...

. They are facultatively aerobic
Aerobic organism
An aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment.Faculitative anaerobes grow and survive in an oxygenated environment and so do aerotolerant anaerobes.-Glucose:...

, but do not produce oxygen in the process of producing energy from light, or phototrophy. Additionally Chloroflexi have a different method of phototrophy (photoheterotroph
Photoheterotroph
Photoheterotrophs are heterotrophic organisms that use light for energy, but cannot use carbon dioxide as their sole carbon source. Consequently, they use organic compounds from the environment to satisfy their carbon requirements. They use compounds such as carbohydrates, fatty acids and...

y) than true photosynthetic bacteria. Phylogenetic analysis
Phylogenetic tree
A phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical and/or genetic characteristics...

 indicates that they had a separate origin.

Whereas most Bacteria, in terms of diversity, are diderms and stain Gram negative with the exception of the Firmicutes
Firmicutes
The Firmicutes are a phylum of bacteria, most of which have Gram-positive cell wall structure. A few, however, such as Megasphaera, Pectinatus, Selenomonas and Zymophilus, have a porous pseudo-outer-membrane that causes them to stain Gram-negative...

(low CG Gram positives), Actinobacteria
Actinobacteria
Actinobacteria are a group of Gram-positive bacteria with high guanine and cytosine content. They can be terrestrial or aquatic. Actinobacteria is one of the dominant phyla of the bacteria....

(high CG gram positives) and the Deinococcus-Thermus group (Gram positive, but diderms with thick peptidoglycan), the members of the phylum Chloroflexi are monoderms and stain mostly Gram negative.

Taxonomy

The currently accepted taxonomy is as follows:
  • Order Chloroflexales
    • Family Chloroflexaceae
      • Genus Chloroflexus Pierson and Castenholz 1974
        • C. aggregans Hanada et al. 1995
        • C. aurantiacus Pierson and Castenholz 1974
      • Chloronema Dubinina and Gorlenko 1975
        • Chloronema giganteum Dubinina and Gorlenko 1975
      • Genus Heliothrix Pierson et al. 1986
        • Heliothrix oregonensis Pierson et al. 1986
      • Genus Roseiflexus Hanada et al. 2002
        • Roseiflexus castenholzii Hanada et al. 2002
    • Family Oscillochloridaceae
      • Genus Oscillochloris Gorlenko and Pivovarova 1989 emend. Keppen et al. 2000
        • O. chrysea Gorlenko and Pivovarova 1989
        • O. trichoides (ex Szafer) Gorlenko and Korotkov1989 emend. Keppen et al. 2000
  • Order Herpetosiphonales
    Herpetosiphonales
    Herpetosiphonales is one of two orders of bacteria in the class Chloroflexi....

    • Family Herpetosiphonaceae
      Herpetosiphonaceae
      Herpetosiphonaceae is a family of bacteria in the order Herpetosiphonales....

      • Genus Herpetosiphon
        Herpetosiphon
        Herpetosiphon is a genus of bacteria in the family Herpetosiphonaceae....

        Holt and Lewin 1968
        • H. aurantiacus Holt and Lewin 1968
        • H. geysericola (Copeland 1936) Lewin 1970


Additionally, there are "Kouleothrix aurantiaca" and "Dehalobium chlorocoercia" which have not been fully described.

Etymology

The name "Chloroflexi" is a Neolatin nominative case masculine plural of "Chloroflexus", which the name of the first genus described. The noun is a combination of the Greek adjective chloros, -a, on (χλωρός, -ά, -όν) meaning "greenish-yellow" and the Latin masculine passive perfect participle flexus (of flecto) meaning "bent" to mean "a green bending". It should be therefore noted that the etymology is not due to chlorine, an element (dephlogisticated muriatic acid air) which was confirmed as such in 1810 by Sir Humphry Davy and named after its pale green colour.
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