Description of 'Synergistetes' phyl. nov. and emended description of the phylum 'Deferribacteres' and of the family Syntrophomonadaceae, phylum 'Firmicutes'.

The number of bacterial phyla has greatly increased in the past decade. Among them, a candidate division named 'Synergistes' was proposed in a phylogenetic study on the global diversity of bacteria. We previously described the genus Jonquetella and suggested that it belonged to this not yet well-delineated candidate phylum. 16S rRNA gene based-phylogeny studies were conducted using four reconstruction methods and 599 sequences forming five datasets were used in an alternative treeing approach. These analyses indicated that the genera Aminiphilus, Aminobacterium, Aminomonas, Anaerobaculum, Dethiosulfovibrio, Jonquetella, Synergistes, Thermanaerovibrio and Thermovirga should be grouped in the same high-level taxon. This taxon was shown to be a phylum-rank lineage in the domain Bacteria and, because of the prior use of the name Synergistes for a genus, the name 'Synergistetes' is proposed for this candidate phylum. We also propose an emended delineation of the phylum 'Deferribacteres', which is now only represented by the family Deferribacteriaceae. The emended family Syntrophomonadaceae is limited to the genera Pelospora, Syntrophomonas, Syntrophothermus and Thermosyntropha.