Taxonomic proposal for a deep branching bacterial phylogenetic lineage: transfer of the family Thermodesulfobiaceae to Thermodesulfobiales ord. nov., Thermodesulfobiia classis nov. and Thermodesulfobiota phyl. nov

The family Thermodesulfobiaceae, comprising one genus Thermodesulfobium with two validly published species, is currently assigned to order Thermoanaerobacterales within the class Clostridia of the phylum Bacillota. At the same time, the very first 16S rRNA gene sequence-based phylogenetic studies of representatives of the genus pointed out great differences between Thermodesulfobium and other members of the phylum Bacillota. Subsequent studies of new Thermodesulfobium representatives supported deep phylogenetic branching of this lineage within bacterial tree, implying that it represents a novel phylum. The results of the phylogenomic analysis performed in the frames of the present work confirm previous findings and suggest that Thermodesulfobium represents a distinct phylum-level lineage. Thus, we propose the transfer of the family Thermodesulfobiaceae to the new order Thermodesulfobiales within the new class Thermodesulfobiia and the new phylum Thermodesulfobiota.