Clostridia Rainey 2010
Thermoanaerobacterales Wiegel 2010
|Families and genera|
The Thermoanaerobacterales is a polyphyletic order of bacteria placed within the polyphyletic class Clostridia, and encompassing four families: the Thermoanaerobacteraceae, the Thermodesulfobiaceae, the Thermoanaerobacterales Family III. Incertae Sedis, and the Thermoanaerobacterales Family IV. Incertae Sedis, and various unplaced genera. 
This order is noted for the species' abilities to survive in extreme environments without oxygen and of relatively elevated temperatures for a living being (up to 80-90°C). An example organism in this order is Thermoanaerobacter ethanolicus.
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI) and the phylogeny is based on 16S rRNA-based LTP release 111 by The All-Species Living Tree Project.
The Thermoanaerobacterales, as previously mentioned, is polyphyletic, and consists of over six morphologically and physiologically similar clades:
- Clostridium thermoamylolyticum ♠ Katkocin et al. 1985
- Desulfovirgula thermocuniculi Kaksonen et al. 2007
- Thermanaeromonas toyohensis Mori et al. 2002
- Thermoanaerobacterales Unnamed clade I [incl. Fervidicola]
- Thermoanaerobacterales Unnamed clade II
♣ International Journal of Systematic Bacteriology or International Journal of Systematic and Evolutionary Microbiology (IJSB/IJSEM) published species that are in press.
♠ Strains found at the National Center for Biotechnology Information (NCBI) but not listed in the List of Prokaryotic names with Standing in Nomenclature (LPSN).
- Sayers; et al. "Thermoanaerobacterales". National Center for Biotechnology Information (NCBI) taxonomy database. Retrieved 2 March 2019.
- C.Michael Hogan. 2010. Extremophile. eds. E.Monosson & C.Cleveland, Encyclopedia of Earth. National Council for Science and the Environment, Washington DC.
- J.P. Euzéby. "Thermoanaerobacterales". List of Prokaryotic names with Standing in Nomenclature (LPSN). Retrieved 2 March 2019.
- All-Species Living Tree Project."16S rRNA-based LTP release 111 (full tree)" (PDF). Silva Comprehensive Ribosomal RNA Database. Retrieved 20 March 2013.