The Chloroflexota 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 (green non-sulfur bacteria); and anaerobic halorespirers, which uses halogenated organics (such as the toxic chlorinated ethenes and polychlorinated biphenyls) as electron acceptors.

[3] In 1987, Carl Woese, regarded as one of the forerunner of the molecular phylogeny revolution, divided Eubacteria into 11 divisions based on 16S ribosomal RNA (SSU) sequences and grouped the genera Chloroflexus, Herpetosiphon and Thermomicrobium into the "green non-sulfur bacteria and relatives",[4][5] which was temporarily renamed as "Chloroflexi" in Volume One of Bergey's Manual of Systematic Bacteriology.

[6] Chloroflexota being a deep branching phylum (see Bacterial phyla), it was considered in Volume One of Bergey's Manual of Systematic Bacteriology to include a single class with the same name.

[10] 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.

[10] The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN)[11] and National Center for Biotechnology Information (NCBI).

[12] Thermoflexus Sphaerobacter Nitrolancea Thermalbibacter Thermomicrobium Thermorudis Kallotenue Herpetosiphon Roseiflexus Heliothrix Oscillochloris Chloroflexus Thermogemmatispora Thermosporothrix Ktedonosporobacter Reticulibacter Ktedonobacter Ktedonospora Tengunoibacter Dictyobacter Tepidiforma Dehalococcoides Dehalogenimonas Litorilinea Caldilinea Aggregatilinea Ardenticatena Thermomarinilinea Flexilinea Ornatilinea Pelolinea Anaerolinea[19][20] Leptolinea[19] Levilinea[19] Bellilinea Longilinea[21] "Ca Dormiibacter" "Ca Aquidulcis" Thermogemmatispora Ktedonosporobacter Ktedonobacter Thermosporothrix Tengunoibacter Dictyobacter Thermobaculum Nitrolancea Sphaerobacter Thermalbibacter Thermomicrobium Thermorudis Kallotenue Herpetosiphon Roseiflexus "Ca.

Villigracilis" Flexilinea "Brevefilum" Pelolinea Ornatilinea Levilinea Leptolinea Anaerolinea Longilinea Bellilinea "Thermanaerothrix" Genus "Candidatus Caldibacter" corrig.

"[6] The etymology is unrelated to chlorine, an element that was discovered in 1810 by Sir Humphry Davy and named after its pale green colour.