Chloroflexota

Lore & Background

The taxon name was created in the 2001 edition of Volume 1 of Bergey's Manual of Systematic Bacteriology and is the Latin plural of the name Chloroflexus, the name of the type genus of the phylum, a common practice. 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', 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), 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% 16S ribosomal RNA 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 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 mor

Reader's Guide

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 phylum includes classes such as Ktedonobacteria, Thermomicrobiia, Chloroflexia, Tepidiformia, and others listed in the taxonomy section. The taxonomy includes genera, families, orders, and classes with both validly published and 'Candidatus' names.

Did You Know?

• Chloroflexota are often incorrectly referred to as green sulfur bacteria; green sulfur bacteria are actually the phylum Chlorobi (now Chlorobiota).
• The phylum Chloroflexota contains eight distinct classes: Anaerolinae, Ardenticatenia, Caldilineae, Chloroflexia, Dehalococcoidia, Ktedonobacteria, Tepidiformia and Thermoflexia.
• Members of Chloroflexota are monoderms (have one cell membrane) but can stain both gram positive and gram negative.
• Recent phylogenetic analysis suggests that the classes Chloroflexi and Thermomicrobia may form a core group, while other classes might represent separate phyla.