# Thermoanaerobacterales

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.

## Taxonomy

The Thermoanaerobacterales, as previously mentioned, is polyphyletic, and consists of numerous morphologically similar clades:
| LPSN & NCBI | 16S rRNA based LTP_01_2022 & 120 marker proteins based GTDB 07-RS207 |
| Thermoanaerobacteraceae Ammonifex Caldanaerobacter Caldanaerobius Caldanaerovirga Calderihabitans Caloribacterium Calorimonas Carboxydothermus Desulfothermobacter Desulfovirgula Fervidicola Gelria Moorella Tepidanaerobacter Thermacetogenium Thermanaeromonas Thermoanaerobacter Thermodesulfitimonas Thermosediminibacter Thermovenabulum Thermovorax Zhaonella Thermodesulfobiaceae Thermodesulfobium Thermoanaerobacterales Family III Anaerocellum Caldicellulosiruptor Syntrophaceticus Thermoanaerobacterium Thermoanaerobacterales Family IV Mahella | "Desulfovirgulaceae" Desulfovirgula Kaksonen et al. 2007 "Ammonificales" "Ammonificaceae" Ammonifex Huber & Stetter 1996 Desulfothermobacter Frolov et al. 2018 Thermodesulfitimonas Slobodkina et al. 2017 "Carboxydothermales" "Carboxydothermaceae" Carboxydothermus Svetlichny et al. 1991 "Mahellales" "Mahellaceae" Mahella Bonilla Salinas et al. 2004 Moorellales Lv et al. 2020 Calderihabitantaceae Lv et al. 2020 Calderihabitans Yoneda et al. 2013 Desulfitibacteraceae Lv et al. 2020 Desulfitibacter Nielsen, Kjeldsen & Ingvorsen 2006 Moorellaceae Lv et al. 2020 Moorella Collins et al. 1994 non Rao & Rao 1964 Thermanaeromonas Mori et al. 2002 "Thermacetogeniaceae" Syntrophaceticus Westerholm, Roos & Schnurer 2011 Thermacetogenium Hattori et al. 2000 "Caldicellulosiruptorales" Bing et al. 2023 "Caldicellulosiruptoraceae" Bing et al. 2023 Caldicellulosiruptor Sissons et al. 1987 Thermoanaerobacterales Wiegel 2010 "Caldanaerobiaceae" Caldanaerobius Lee et al. 2008 Caloribacterium Slobodkina et al. 2012 "Calorimonadaceae" Calorimonas Khomyakova et al. 2020 Thermoanaerobacteraceae Wiegel 2010 Caldanaerobacter Fardeau et al. 2004 Thermoanaerobacter Wiegel & Ljungdahl 1982 Thermoanaerobacterium Lee et al. 1993 Zhaonellaceae Lv et al. 2020 Zhaonella Lv et al. 2020 "Thermodesulfobiales" Cavalier-Smith 2020 Thermodesulfobiaceae Morie et al. 2004 Thermodesulfobium Morie et al. 2004 Thermosediminibacterales Zhang et al. 2019 Tepidanaerobacteraceae Zhang et al. 2019 Biomaibacter Zhang et al. 2019 Tepidanaerobacter Sekiguchi et al. 2006 Thermosediminibacteraceae Zhang et al. 2019 Fervidicola Ogg & Patel 2009 Caldanaerovirga Wagner et al. 2009 Thermosediminibacter Lee et al. 2006 Thermovenabulum Zavarzina et al. 2002 Thermovorax Makinen, Kaksonen & Puhakka 2012 |

## Phylogeny

| 16S rRNA based LTP_08_2023 | 120 marker proteins based GTDB 08-RS214. |
| "Carboxydothermales" * "Carboxydothermaceae" Carboxydothermus "Thermacetogeniales" * "Thermacetogeniaceae" Syntrophaceticus Thermacetogenium Moorellales * Moorellaceae Moorella "Calderihabitantales" * Calderihabitantaceae Calderihabitans Koleobacterales Koleobacteraceae Koleobacter Zhaonellaceae * Zhaonella "Desulfitibacterales" * Desulfitibacteraceae Desulfitibacter Desulfitisporaceae Desulfitispora "Syntrophomonadales" Syntrophomonadaceae "Caldanaerobiaceae" * Caldanaerobius Caloribacterium Calorimonas Thermoanaerobacterium * [incl. Thermohydrogenium] "Dictyoglomerales" "Dictyoglomeraceae" Dictyoglomus "Caldicellulosiruptorales" * "Caldicellulosiruptoraceae" Caldicellulosiruptor DSM‑22653 DSM‑22653 Brockia Hydrogenibacillus "Ammonificales" * "Ammonificales" Thermodesulfitimonas Desulfothermobacter Ammonifex Thermosediminibacterales * Thermoanaerobacterales * "Desulfovirgulaceae" Desulfovirgula Thermanaeromonas Thermoanaerobacteraceae Caldanaerobacter Thermoanaerobacter | DSM‑12270 * "Thermacetogeniales" "Thermacetogeniaceae" Thermacetogenium Syntrophaceticus "Moorellia" * DULZ01 Zhaonellaceae Zhaonella "Calderihabitantales" "Calderihabitantaceae" Calderihabitans "Desulfitibacterales" "Desulfitibacteraceae" Desulfitibacter Moorellales Moorellaceae Thermanaeromonas Moorella "Carboxydocellia" "Carboxydocellales" "Carboxydocellaceae" Carboxydocella "Thermincolia" "Thermincolales" "Carboxydothermia" * "Carboxydothermales" "Carboxydothermaceae" Carboxydothermus "Desulfotomaculia" "Ammonificales" "Desulforudaceae" "Ammonificaceae" * Ammonifex Thermodesulfitimonas "Desulfotomaculales" "Thermosediminibacteria" Koleobacterales Thermosediminibacterales * "Thermoanaerobacteria" * "Caldicellulosiruptorales" "Caldicellulosiruptoraceae" Caldicellulosiruptor Thermoanaerobacterales "Caldanaerobiaceae" Calorimonas "Caldanaerobiaceae" Caldanaerobius Thermoanaerobacteraceae Thermoanaerobacterium Caldanaerobacter Thermoanaerobacter "Clostridiia" s.s. |
Note:
* polyphyletic Thermoanaerobacterales