Chloroflexi

Chloroflexi is a phylum of filamentous bacteria that is structurally and phylogenetically Gram positive because it is monodermic, that is, it has a single cell membrane. However, Gram staining presents different results, sometimes staining as Gram negative, depending on the thickness of the cell wall which can be very thin. Previously they were known as non-sulfur green bacteria, however This is not completely correct because not all of these bacteria are photosynthetic green, and some may use reduced sulfur compounds as electron donors.

They tend to form colonies enclosed in typically filamentous envelopes, and they move by sliding over surfaces. Many species are thermophiles.

Thermomicrobia was once considered a phylum, but is now a class within Chloroflexi. Cavalier-Smith calls these two groups Chlorobacteria and considers them to be the most primitive. In 2020 Cavalier-Smith, in an analysis of multiple ribosomal proteins, found that Chloroflexi make up the most basal group of all cellular organisms, while bacteria are a paraphyletic group with respect to archaea and eukaryotes.

Groups

• Anaerolineae: Mesophile or thermophiles filamentous bacteria that inhabit wastewater, mud and deep sea subsoil, with a heterotrophic anaerobic metabolism.
• Caldilineae: Thermophiles and mesophiles. They are negative Gram, anaerobics or aerobics chemoorganotrophas.
• Chloroflexia: Generally photosynthetic, filamentous, often thermophiles. They can be non-photosynthetics and browns in the dark and then phototrophas and greens in the light as Chloroflexus.
• Dehalococcoidia o Dehalococcoidetes: Inhabitant of the marine subsoil and in aquifers under the surface of the Earth, where anaerobically intervenes in the dislocation of chlorinated compounds.
• Ktedonobacteria: Aerobic bacteria Gram positive mycelium and spores forming machines.
• Thermomicrobia: They are positive or negative Gram heterotrophae thermophiles.

Phylogeny

Chloroflexi could be related to other phyla such as Cyanobacteria, Deinococcus-Thermus and the Gram positive Firmicutes and Actinobacteria. However, phylogenetic trees are not conclusive.

Based on 16S rRNA phylogenetic analysis, the subgroups are related as follows: