The Chloroflexota are a phylum of bacteria containing isolates with a diversity of phenotypes, including members that are

aerobic Aerobic means "requiring air," in which "air" usually means oxygen. Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics, a form of aerobic exercise * Aerobic respiration, the aerobic process of cellu ...

thermophile A thermophile is an organism—a type of extremophile—that thrives at relatively high temperatures, between . Many thermophiles are archaea, though they can be bacteria or fungi. Thermophilic eubacteria are suggested to have been among the ea ...

s, which use oxygen and grow well in high temperatures; anoxygenic phototrophs, which use light for photosynthesis (

green non-sulfur bacteria The Chloroflexia are a class of bacteria in the phylum Chloroflexota, known as filamentous green non-sulfur bacteria. They use light for energy and are named for their green pigment, usually found in photosynthetic bodies called chlorosomes. Chl ...

); and

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: * Anaerobic adhesive, a bonding a ...

halorespirers, which uses halogenated organics (such as the toxic chlorinated

ethenes Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene ...

and

polychlorinated biphenyl Polychlorinated biphenyls (PCBs) are highly carcinogenic chemical compounds, formerly used in industrial and consumer products, whose production was banned in the United States by the Toxic Substances Control Act in 1979 and internationally by t ...

s) as electron acceptors. The members of the phylum ''Chloroflexota'' are monoderms (that is, have one cell membrane with no outer membrane), but they stain mostly gram-negative. Many well-studied phyla of bacteria are

diderms Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall s ...

and stain gram-negative, whereas well-known monoderms that stain Gram-positive include ''Firmicutes'' (or ''

Bacillota The Bacillota (synonym Firmicutes) are a phylum of bacteria, most of which have gram-positive cell wall structure. The renaming of phyla such as Firmicutes in 2021 remains controversial among microbiologists, many of whom continue to use the ear ...

'') ( low G+C gram-positives), ''

Actinomycetota The ''Actinomycetota'' (or ''Actinobacteria'') are a phylum of all gram-positive bacteria. They can be terrestrial or aquatic. They are of great economic importance to humans because agriculture and forests depend on their contributions to soi ...

'' (high-G+C gram-positives) and ''

Deinococcota ''Deinococcota'' (synonym, ''Deinococcus-Thermus'') is a phylum of bacteria with a single class, ''Deinococci'', that are highly resistant to environmental hazards, also known as extremophiles. These bacteria have thick cell walls that give them ...

'' (gram-positive diderms with thick peptidoglycan).

History

The taxon name was created in the 2001 edition of Volume 1 of

Bergey's Manual of Systematic Bacteriology ''Bergey's Manual of Systematic Bacteriology'' is the main resource for determining the identity of prokaryotic organisms, emphasizing bacterial species, using every characterizing aspect. The manual was published subsequent to the ''Bergey's Man ...

and is the Latin plural of the name ''

Chloroflexus Chloroflexales is an order of bacteria in the class Chloroflexia. Taxonomy The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI). ...

'', the name of the type genus of the phylum, a

common practice In European art music, the common-practice period is the era of the tonal system. Most of its features persisted from the mid-Baroque period through the Classical and Romantic periods, roughly from 1650 to 1900. There was much stylistic evolutio ...

. In 1987,

Carl Woese Carl Richard Woese (; July 15, 1928 – December 30, 2012) was an American microbiologist and biophysicist. Woese is famous for defining the Archaea (a new domain of life) in 1977 through a pioneering phylogenetic taxonomy of 16S ribosomal RNA, ...

, regarded as one of the forerunner of the molecular phylogeny revolution, divided Eubacteria into 11 divisions based on

16S ribosomal RNA 16 S ribosomal RNA (or 16 S rRNA) is the RNA component of the 30S subunit of a prokaryotic ribosome (SSU rRNA). It binds to the Shine-Dalgarno sequence and provides most of the SSU structure. The genes coding for it are referred to as 16S rRN ...

(SSU) sequences and grouped the genera ''

'', ''

Herpetosiphon ''Herpetosiphon'' is a genus of bacteria in the family '' Herpetosiphonaceae''. Phylogeny References {{Taxonbar, from=Q16965551 Phototrophic bacteria Bacteria genera Chloroflexota ...

'' and '' Thermomicrobium'' into the "green non-sulfur bacteria and relatives", which was temporarily renamed as "Chloroflexi" in Volume One of Bergey's Manual of Systematic Bacteriology. Chloroflexota being a deep branching phylum (see

Bacterial phyla Bacterial phyla constitute the major lineages of the domain '' Bacteria''. While the exact definition of a bacterial phylum is debated, a popular definition is that a bacterial phylum is a monophyletic lineage of bacteria whose 16S rRNA genes ...

), it was considered in Volume One of Bergey's Manual of Systematic Bacteriology to include a single class with the same name. Since 2001, however, new classes have been created thanks to newly discovered species, and the phylum Chloroflexi is now divided into several classes. " Dehalococcoidetes" is a placeholder name given by Hugenholtz & Stackebrandt, 2004, after "''Dehalococcoides ethenogenes''" a species partially described in 1997. The first species fully described was ''Dehalogenimonas lykanthroporepellens'', by Moe et al. 2009, but in the description of that species the class was not made official nor were families or orders laid out as the two species share only 90%

identity, meaning that they could fall in different families or even orders. Recent phylogenetic analysis of the Chloroflexota has found very weak support for the grouping together of the different classes currently part of the phylum. The six classes that make up the phylum did not consistently form a well-supported clade in phylogenetic trees based on concatenated sequences for large datasets of proteins, and no

conserved signature indels Conserved signature inserts and deletions (CSIs) in protein sequences provide an important category of molecular markers for understanding phylogenetic relationships. CSIs, brought about by rare genetic changes, provide useful phylogenetic markers ...

were identified that were uniquely shared by the entire phylum. However, the classes Chloroflexi and Thermomicrobia were found to group together consistently by both the usual phylogenetic means and the identification of shared conserved signature indels in the 50S ribosomal protein L19 and the enzyme UDP-glucose 4-epimerase. It has been suggested that the phylum Chloroflexi ''sensu stricto'' should comprise only the classes Chloroflexi and Thermomicrobia, and the other four classes ("Dehalococcoidetes," Anaerolineae, Caldilineae and Ktedonobacteria) may represent one or more independent phyla branching in the neighborhood of the Chloroflexi.

Phylogeny

The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI).

Taxonomy

Genus "''Candidatus'' Chlorotrichoides" corrig. Oren et al. 2020 Chlorothrix"_Klappenbach_&_Pierson_2004_non_Dyar_1921_non_Berger-Perrot_1982.html" ;"title="Chlorothrix_(bacterium).html" ;"title="''Candidatus'' Chlorothrix (bacterium)">Chlorothrix" Klappenbach & Pierson 2004 non Dyar 1921 non Berger-Perrot 1982">Chlorothrix_(bacterium).html" ;"title="''Candidatus'' Chlorothrix (bacterium)">Chlorothrix" Klappenbach & Pierson 2004 non Dyar 1921 non Berger-Perrot 1982br /> Genus "''Candidatus'' Nitrocaldera" Spieck et al. 2020
Genus "''Candidatus'' Nitrotheca" Spieck et al. 2020
Class "Limnocylindria" Mehrshad et al. 2018 *Order "Limnocylindrales" Mehrshad et al. 2018 **Family " Limnocylindraceae" Mehrshad et al. 2018 (SL56) ***Genus "''Candidatus'' Aquidulcis" corrig. Rodriguez-R et al. 2020 ***Genus "''Candidatus'' Limnocylindrus" Mehrshad et al. 2018 Class Ktedonobacteria Cavaletti et al. 2007 emend. Yabe et al. 2010 *Order Thermogemmatisporales Yabe et al. 2011 **Family Thermogemmatisporaceae Yabe et al. 2011 ***Genus '' Thermogemmatispora'' Yabe et al. 2011 *Order Ktedonobacterales Cavaletti et al. 2007 **Family Dictyobacteraceae Wang et al. 2019 ***Genus '' Dictyobacter'' Yabe et al. 2017 ***Genus '' Tengunoibacter'' Wang et al. 2019 **Family Ktedonobacteriaceae Cavaletti et al. 2007 ***Genus '' Ktedonobacter'' corrig. Cavaletti et al. 2007 ***Genus '' Ktedonospora'' Yabe et al. 2021 **Family Ktedonosporobacteraceae Yan et al. 2020 ***Genus '' Ktedonosporobacter'' Yan et al. 2020 **Family Reticulibacteraceae Yabe et al. 2021 ***Genus '' Reticulibacter'' Yabe et al. 2021 **Family Thermosporotrichaceae Yabe et al. 2010 ***Genus '' Thermosporothrix'' Yabe et al. 2010 Class " Umbricyclopia" Mehrshad et al. 2018 *Order " Umbricyclopales" Mehrshad et al. 2018 **Family " Umbricyclopaceae" Mehrshad et al. 2018 ***Genus "''Candidatus'' Umbricyclops" Mehrshad et al. 2018 (TK10) Class " Bathosphaeria" Mehrshad et al. 2018 *Order " Bathosphaerales" Mehrshad et al. 2018 **Family " Bathosphaeraceae" Mehrshad et al. 2018 ***Genus "''Candidatus'' Bathosphaera" Mehrshad et al. 2018 (JG30-KF-CM66) Class Tepidiformia Kochetkova et al. 2020 *Order Tepidiformales Kochetkova et al. 2020 **Family Tepidiformaceae Kochetkova et al. 2020 ***Genus "'' Tepidiforma'' Kochetkova et al. 2020 Class

Dehalococcoidia ''Dehalococcoidia'' is a class of Chloroflexota, a phylum of Bacteria. It is also known as the DHC group. The name ''Dehalococcoidetes'' is a placeholder name given by Hugenholtz and Stackebrandt, 2004, after ''Dehalococcoides ethenogenes'', a ...

Löffler et al. 2013 *Order Dehalococcoidales Löffler et al. 2013 **Family Dehalococcoidaceae Löffler et al. 2013 ***Genus ''

Dehalococcoides ''Dehalococcoides'' is a genus of bacteria within class Dehalococcoidia that obtain energy via the oxidation of hydrogen and subsequent reductive dehalogenation of halogenated organic compounds in a mode of anaerobic respiration called organo ...

'' Löffler et al. 2013 ***Genus '' Dehalogenimonas'' Moe et al. 2009 Class " Thermofontia" corrig. Ward et al. 2018 *Order " Phototrophicales" Zheng et al. 2022 **Family " Phototrophicaceae" Zheng et al. 2022 ***Genus "'' Phototrophicus''" Zheng et al. 2022 Class Ardenticatenia Kawaichi et al. 2013 *Order Ardenticatenales Kawaichi et al. 2013 **Family Ardenticatenaceae Kawaichi et al. 2013 ***Genus '' Ardenticatena'' Kawaichi et al. 2013 Class " Caldilineia" Oren, Parte & Garrity 2016 ex Cavalier-Smith 2020 *Order Caldilineales Yamada et al. 2006 **Family " Amarolineaceae" Andersen et al. 2019 ***Genus "''Candidatus'' Amarolinea" Andersen et al. 2019 **Family Caldilineaceae Yamada et al. 2006 ***Genus '' Caldilinea'' Sekiguchi et al. 2003 ***Genus '' Litorilinea'' Kale et al. 2013 Class Thermoflexia Dodsworth et al. 2014 *Order Thermoflexales Dodsworth et al. 2014 **Family Thermoflexaceae Dodsworth et al. 2014 ***Genus "''Candidatus'' Roseilinea" Thiel et al. 2016 ***Genus '' Thermoflexus'' Dodsworth et al. 2014 Class " Anaerolineia" Oren, Parte & Garrity 2016 *Family " Profundisolitariaceae" Mehrshad et al. 2018 **Genus "''Candidatus'' Profundisolitarius" Mehrshad et al. 2018 (CL500-11) *Order " Promineifilales" **Family " Promineifilaceae" ***Genus "''Candidatus'' Promineofilum" McIlroy et al. 2016 *Order Aggregatilineales Nakahara et al. 2019 **Family Aggregatilineaceae Nakahara et al. 2019 ***Genus '' Aggregatilinea'' Nakahara et al. 2019 *Order Anaerolineales Yamada et al. 2006 **Family Anaerolineaceae Yamada et al. 2006 ***Genus '' Anaerolinea'' Sekiguchi et al. 2003 emend. Yamada et al. 2006 ***Genus '' Bellilinea'' Yamada et al. 2007 ***Genus "'' Brevefilum''" McIlroy et al. 2017 ***Genus "''Candidatus'' Denitrolinea" Okubo et al. 2021 ***Genus "'' Desulfolinea''" Van Vliet et al. 2020 ***Genus '' Flexilinea'' Sun et al. 2015 ***Genus '' Levilinea'' Yamada et al. 2006 ***Genus '' Leptolinea'' Yamada et al. 2006 ***Genus '' Longilinea'' Yamada et al. 2007 ***Genus '' Ornatilinea'' Podosokorskaya et al. 2013 ***Genus '' Pelolinea'' Imachi et al. 2014 ***Genus '' Thermomarinilinea'' Nunoura et al. 2013 ***Genus "'' Thermanaerothrix''" Gregoire et al. 2011 ***Genus "''Candidatus''" Villigracilis'' Nierychlo et al. 2019 Class Thermomicrobiia Oren, Parte & Garrity 2016 *Order

Sphaerobacterales ''Sphaerobacter'' is a genus of bacteria. When originally described it was placed in its own subclass (Spahaerobacteridae) within the class Actinomycetota. Subsequently, phylogenetic studies have now placed it in its own order Sphaerobacterales ...

Stackebrandt, Rainey & Ward-Rainey 1997 **Family Sphaerobacteraceae Stackebrandt, Rainey & Ward-Rainey 1997 ***Genus '' Nitrolancea'' Sorokin et al. 2014 ''Nitrolancetus''"_Sorokin_et_al._2012.html" ;"title="Nitrolancetus.html" ;"title="''Nitrolancetus">''Nitrolancetus''" Sorokin et al. 2012">Nitrolancetus.html" ;"title="''Nitrolancetus">''Nitrolancetus''" Sorokin et al. 2012***Genus ''Sphaerobacter'' Demharter et al. 1989 *Order Thermomicrobiales Garrity & Holt 2002 **Family Thermomicrobiaceae Garrity & Holt 2002 ***Genus '' Thermomicrobium'' Jackson, Ramaley & Meinschein 1973 ***Genus '' Thermorudis'' King & King 2014 Class

Chloroflexia The Chloroflexia are a class of bacteria in the phylum Chloroflexota, known as filamentous green non-sulfur bacteria. They use light for energy and are named for their green pigment, usually found in photosynthetic bodies called chlorosomes. Chl ...

Gupta et al. 2013 *Genus "'' Dehalobium''" Wu et al. 2002 *Genus "''Candidatus'' Lithoflexus" Saghai et al. 2020 *Genus "''Candidatus'' Sarcinithrix" Nierychlo et al. 2019 *Order " Thermobaculales" **Family " Thermobaculaceae" ***Genus "'' Thermobaculum''" Botero et al. 2004 *Order Kallotenuales Cole et al. 2013 **Family Kallotenuaceae Cole et al. 2013 ***Genus '' Kallotenue'' Cole et al. 2013 *Order

Herpetosiphonales Herpetosiphonales is an order of bacteria in the class Chloroflexia The Chloroflexia are a class of bacteria in the phylum Chloroflexota, known as filamentous green non-sulfur bacteria. They use light for energy and are named for their green p ...

Gupta et al. 2013 **Family

Herpetosiphonaceae ''Herpetosiphonaceae'' is a family of bacteria in the order '' Herpetosiphonales''. References External links Phototrophic bacteria Chloroflexota {{bacteria-stub ...

Gupta et al. 2013 ***Genus "''Candidatus'' Anthektikosiphon" Ward, Fischer & McGlynn 2020 ***Genus ''

Herpetosiphon ''Herpetosiphon'' is a genus of bacteria in the family '' Herpetosiphonaceae''. Phylogeny References {{Taxonbar, from=Q16965551 Phototrophic bacteria Bacteria genera Chloroflexota ...

'' Holt & Lewin 1968 'Flavilitoribacter''_García-López_et_al._2020.html" ;"title="Flavilitoribacter.html" ;"title="'Flavilitoribacter">'Flavilitoribacter'' García-López et al. 2020">Flavilitoribacter.html" ;"title="'Flavilitoribacter">'Flavilitoribacter'' García-López et al. 2020*Order Chloroflexales Gupta et al. 2013 **Suborder Roseiflexineae Gupta et al. 2013 ***Family Roseiflexaceae Gupta et al. 2013 ["Kouleotrichaceae" Mehrshad et al. 2018] ****Genus "'' Kouleothrix''" Kohno et al. 2002 ****Genus '' Heliothrix'' Pierson et al. 1986 ****Genus '' Roseiflexus'' Hanada et al. 2002 **Suborder Chloroflexineae Gupta et al. 2013 ***Family Chloroflexaceae Gupta et al. 2013 ****Genus ''Candidatus'' Chloranaerofilum Thiel et al. 2016 ****Genus ''

'' Pierson & Castenholz 1974 ''Chlorocrinis''".html" ;"title="Chlorocrinis.html" ;"title="''Chlorocrinis">''Chlorocrinis''"">Chlorocrinis.html" ;"title="''Chlorocrinis">''Chlorocrinis''"***Family Oscillochloridaceae Gupta et al. 2013 ****Genus ''Candidatus'' Chloroploca Gorlenko et al. 2014 ****Genus ''Chloronema'' ♪ Dubinina & Gorlenko 1975 ****Genus ''Oscillochloris'' Gorlenko & Pivovarova 1989 ****Genus ''Candidatus'' Viridilinea Grouzdev et al. 2018

Etymology

The name ''Chloroflexi'' is a Neolatin nominative case masculine plural of ''

'', which is 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." The etymology is unrelated to

chlorine Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is ...

, an element that was discovered in 1810 by

Sir Humphry Davy Sir Humphry Davy, 1st Baronet, (17 December 177829 May 1829) was a British chemist and inventor who invented the Davy lamp and a very early form of arc lamp. He is also remembered for isolating, by using electricity, several elements for the ...

and named after its pale green colour. Another phylum with the same root is ''

Chlorobiota The green sulfur bacteria are a phylum of obligately anaerobic photoautotrophic bacteria that metabolize sulfur. Green sulfur bacteria are nonmotile (except ''Chloroherpeton thalassium'', which may glide) and capable of anoxygenic photosynthes ...

'', whereas "'' Cyanobacteria''" has the root ''cyanos'' (''κύανος''), meaning "blue-green." Unlike some other phyla, there is no theme root in the name of genera of Chloroflexota, and in fact many genera beginning with "''Chloro-''" or ending in ''"-chloris"'' are either cyanobacteria or chlorobi.

References

{{DEFAULTSORT:Chloroflexota Phototrophic bacteria Bacteria phyla Chloroflexota