History Chloroflexi (phylum)

the taxon name created in 2001 edition of volume 1 of bergey s manual of systematic bacteriology , latin plural of name chloroflexus, name of type genus of phylum, common practice.

in 1987, carl woese, regarded forerunner of molecular phylogeny revolution, divided eubacteria 11 divisions based on 16s ribosomal rna (ssu) sequences , grouped genera chloroflexus, herpetosiphon , thermomicrobium green non-sulfur bacteria , relatives , temporarily renamed chloroflexi in volume 1 of bergey s manual of systematic bacteriology.

being deep branching phylum (cf. bacterial phyla) classification analysed in volume 1 of bergey s manual of systematic bacteriology , included single class same name, class chloroflexi. since 2001 however, new classes have been created newly discovered species, therefore phylum chloroflexi divided into:

chloroflexi gupta et al. 2012
thermomicrobia hugenholtz & stackebrandt, 2004
dehalococcoidetes hugenholtz & stackebrandt, 2004
anaerolineae yamada et al., 2006
caldilineae yamada et al., 2006
ktedonobacteria cavaletti et al., 2007 emend. yabe et al., 2010

regarding class dehalococcoidetes , placeholder name given hugenholtz & stackebrandt, 2004, after dehalococcoides ethenogenes partially described species in 1997, whereas first species described dehalogenimonas lykanthroporepellens moe et al. 2009, in description of species class not made official nor families or orders laid out 2 species share 90% 16s identity, meaning fall in different families or orders.

recent phylogenetic analysis of chloroflexi has found weak support grouping of different classes part of phylum. 6 classes make phylum did not consistently form well-supported monophyletic clade in phylogenetic trees based on concatenated sequences large datasets of proteins , no conserved signature indels identified uniquely shared entire phylum. however, classes chloroflexi , thermomicrobia found group consistently both usual phylogenetic means , identification of shared conserved signature indels in 50s ribosomal protein l19 , enzyme udp-glucose 4-epimerase. has been suggested phylum chloroflexi sensu stricto should comprise classes chloroflexi , thermomicrobia, , other 4 classes ( dehalococcoidetes, anaerolineae, caldilineae , ktedonobacteria) may represent 1 or more independent phyla branching in neighborhood of chloroflexi.