This article lists the orders of the Bacteria. 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 132 by The All-Species Living Tree Project.All-Species Living Tree Project.
Phylogeny National Center for Biotechnology Information (NCBI) taxonomy was initially used to decorate the genome tree via tax2tree. The 16S rRNA-based Greengenes taxonomy is used to supplement the taxonomy particularly in regions of the tree with no cultured representatives. List of Prokaryotic names with Standing in Nomenclature (LPSN) is used as the primary taxonomic authority for establishing naming priorities. Taxonomic ranks are normalised using phylorank and the taxonomy manually curated to remove polyphyletic groups.
Cladogram was taken from GTDB release 11-RS232 (15th April 2026).
Kingdom Bacillati Phylum "Sysuimicrobiota" Class "Sysuimicrobiia" Liu et al. 2024 [CSP1-3] "Sysuimicrobiales" Liu et al. 2024
Phylum Deinococcota "Deinococcia" Cavalier-Smith 2020 Deinococcales Rainey et al. 1997 (Thermales; Trueperales) (radio-resistant micrococci)
Phylum Chloroflexota
Class "Bathosphaeria" Mehrshad et al. 2018 ?"Bathosphaerales" Mehrshad et al. 2018 [JG30-KF-CM66] Class "Martimicrobia" Williams et al. 2024 ?"Martimicrobiales" Williams et al. 2024 Class "Poriflexia" Kogawa et al. 2022 ?"Ca. Poriflexus" Kogawa et al. 2022 Class "Spiritibacteria" Williams et al. 2024 ?"Spiritibacterales" Williams et al. 2024 Class "Tarhunnaeia" Williams et al. 2024 ?"Tarhunnaeales" Williams et al. 2024 Class "Uliximicrobia" Williams et al. 2024 ?"Uliximicrobiales" Williams et al. 2024 Class "Umbricyclopia" Mehrshad et al. 2018 ?"Umbricyclopales" Mehrshad et al. 2018 (TK10) Class "Dormiibacteria" (sic) Montgomery et al. 2021 (AD3) "Aeolococcales" Montgomery et al. 2021 "Dormibacterales" (sic) Montgomery et al. 2021 Class "Limnocylindria" Mehrshad et al. 2018 "Limnocylindrales" Mehrshad et al. 2018 ["Edaphomicrobiales"] (SL56) Class Ktedobacteria corrig. Cavaletti et al. 2007 Ktedonobacterales corrig. Cavaletti et al. 2007 [Thermogemmatisporales] Class Chloroflexia Gupta et al. 2013 Chloroflexales Gupta et al. 2013 (Herpetosiphonales, Kallotenuales) "Chloroheliales" Tsuji et al. 2024 "Thermobaculales" Chuvochina et al. 2023 Thermomicrobiales Garrity & Holt 2002 (Sphaerobacterales) Class Dehalococcoidia Löffler et al. 2013 Dehalococcoidales Löffler et al. 2013 "Lucifugimonadales" Lim et al. 2023 ["Monstramariales"; "Australimonadales"] Tepidiformales Kochetkova et al. 2020 Class "Caldilineia" Oren, Parte & Garrity 2016 ex Cavalier-Smith 2020 Aggregatilineales Nakahara et al. 2019 ["Phototrophicales"] "Amarolineaceae" Andersen et al. 2019 {SSC4} Anaerolineales Yamada et al. 2006 Ardenticatenales Kawaichi et al. 2013 Caldilineales Yamada et al. 2006 "Epilineales" Petriglieri et al. 2023 "Roseilineaceae" Ward et al. 2021 {J036} "Promineifilales" corrig. Chuvochina et al. 2023 Thermoflexales Dodsworth et al. 2014
Phylum "Elulimicrobiota" Class "Elulimicrobiia" Rodriguez-R et al. 2020 ?"Elulimicrobiales" Rodriguez-R et al. 2020
Phylum Minisyncoccota
Class "Wirthbacteria" (CG2-30-54-11) Class "Dojkabacteria" (WS6) Class "Katanobacteria" (WWE3) Class "Microgenomatia" "Amesbacteraceae" {CAZETR01} "Chazhemtobacteriales" Pallen, Rodriguez-R & Alikhan 2022 [UBA1400] "Curtissbacterales" "Daviesbacterales" "Gottesmanbacterales" (UBA10105) "Levybacterales" "Roizmanbacterales" (UBA1406) "Shapirobacterales" (UBA12405) "Woykebacterales" (RIF34) UBA8517 [incl. "Blackburnbacteraceae"; "Woesebacteraceae"] Class "Gracilibacteria" Yakimov et al. 2022 "Absconditabacterales" (sic) Yakimov et al. 2022 ["Vampirococcales"] "Abawacabacterales" (RBG-16-42-10; RIF46) "Candidatus Altimarinus" Rinke et al. 2013 {BD1-5: UBA6164} (GN02) "Fallacibacteriales" (DOLZORAL124_38_8; UBA4473; "Fertabacterales") "Peregrinibacterales" (UBA1369) "Peribacterales" Anantharaman et al. 2016 Class "Kazanbacteria" (Kazan) Class "Howlettbacteria" (CPR2) Class "Nanosomnibacteria" Tan et al. 2026 ["Berkelbacteria" (sic)] (ACD58) "Nanosomnibacterales" Tan et al. 2026 Class Nanosynbacteria Hendrickson et al. 2026 (TM7) Nanosynbacterales Hendrickson et al. 2026 ["Nanosyncoccales"; "Nanogingivalales"; "Nanoperiodontomorbales"; "Saccharimonadales"] "Parviradicicolales" Wang et al. 2026 (QS-5-54-17) Class ?"Baikalibacteria" Haro-Moreno et al. 2023 Class "Andersenbacteria" (RIF9) Class "Doudnabacteria" (SM2F11) Class "Torokbacteria" (GCA-2792135) Class "Patescibacteriia" Dutkiewicz et al. 2025 (ABY1) ?"Brownbacterales" "Buchananbacterales" (sic) (RIF37) "Jacksonbacterales" (sic) (UBA9629) (RIF38; UBA9629) "Kerfeldbacterales" (sic) (RIF4; SBBC01) "Komeilibacterales" (sic) (RIF6; UBA1558) "Kuenenbacterales" (sic) (UBA2196) "Magasanikbacterales" "Moisslbacterales" [UBA2591] "Patescibacteriales" Dutkiewicz et al. 2025 ["Falkowbacterales"] "Uhrbacterales" (SG8-24) "Veblenbacterales" (RIF39) Class Minisyncoccia Nakajima et al. 2025 "Azambacterales" (sic) (UBA10092) "Giovannonibacteraceae" (sic) {UBA11713} ?"Montesolbacterales" "Moranbacterales" (OD1-i) "Niyogibacteraceae" {HO2-45-28} (RIF11) Minisyncoccales Nakajima et al. 2025 ["Paceibacterales" Chuvochina et al. 2023] "Parcunitrobacterales" Castelle et al. 2017 (GWA2-38-13b) "Phycocordibacterales" Jonas et al. 2025 "Portnoybacterales" (RIF22) "Ryanbacterales" (RIF10) "Spechtbacterales" (RIF19) "Sungbacterales" (RIF17) "Tagabacteraceae" {JAHISW01} (RIF12) "Terrybacteraceae" (RIF13) UBA6257 "Yanofskybacterales" (sic) (2-02-FULL-40-12)
Phylum Armatimonadota
Class UBA5829 ?"Candidatus Hippobium" Gilroy et al. 2022 {UBA5829: UBA5829} Class Fimbriimonadia Im et al. 2012 Fimbriimonadales Im et al. 2012 Class Chthonomonadia Oren, Parte & Garrity 2016 Chthonomonadales Lee et al. 2011 Class Armatimonadia Tamaki et al. 2011 (OP10) Armatimonadales Tamaki et al. 2011 Class "Heboniibacteriia" corrig. Carlton et al. 2023 "Heboniibacterales" corrig. Carlton et al. 2023 Class "Zipacnadia" Carlton et al. 2023 (UBA5377) "Zipacnadales" Carlton et al. 2023 Class Abditibacteriia Tahon et al. 2018 (FBP) Abditibacteriales Tahon et al. 2018 Class Fervidibacteria Nou et al. 2025 Fervidibacterales Nou et al. 2025
Phylum Vulcanimicrobiota
Class "Eudoremicrobiia" (sic) Paoli et al. 2022 ?"Eudoremicrobiales" (sic) Paoli et al. 2022 Class "Xenobia" Ji et al. 2021 (UBP9) "Xenobiales" Ji et al. 2021 Class Vulcanimicrobiia Yabe et al. 2024 (WPS2) "Eremiobacterales" Ward, Cardona & Holland-Moritz 2019 Vulcanimicrobiales Yabe et al. 2024 ("Baltobacterales"; "Palusbacterales"; "Rubrimentiphilales")
Phylum Actinomycetota
Class ?"Syntrophaliphaticia" corrig. Liu et al. 2020 Class "Aquicultoria" Jiao et al. 2021 "Aquicultorales" Jiao et al. 2021 "Geothermocultorales" Jiao et al. 2021 "Oleimmundimicrobiales" Pallen, Rodriguez-R & Alikhan 2022 "Subteraquimicrobiales" Jiao et al. 2021 Class Coriobacteriia König 2013 Anaerosomatales Khomyakova et al. 2023 Coriobacteriales Stackebrandt et al. 1997 (Eggerthellales) Class "Geothermincolia" Jiao et al. 2021 "Geohydrothermomicrobiales" Pallen, Rodriguez-R & Alikhan 2022 [Fen-727] "Geothermincolales" Jiao et al. 2021 Class "Humimicrobiia" Jiao et al. 2021 "Hakubellales" corrig. Merino et al. 2020 "Humimicrobiales" Jiao et al. 2021 Class Rubrobacteria Suzuki 2013 Rubrobacterales Rainey et al. 1997 Class Thermoleophilia Suzuki & Whitman 2013 Gaiellales Albuquerque et al. 2012 Miltoncostaeales Li et al. 2021 Thermoleophilales Reddy & Garcia-Pichel 2009 (Solirubrobacterales) Class Acidimicrobiia Norris 2013 Acidimicrobiales Stackebrandt, Rainey & Ward-Rainey 1997 (Iamiales) "Actinomarinales" Ghai et al. 2013 "Spongiisociales" corrig. Nguyen 2022 ("Benthobacterales") Class "Aridivitia" Ortiz et al. 2021 [CADDZG01] "Aridivitales" Ortiz et al. 2021 (CADDZG01) "Bungeriellales" Tan et al. 2026 (JAHWKV01) Class Nitriliruptoria Ludwig et al. 2013 Euzebyales Kurahashi et al. 2010 (Egibacterales,Stomatohabitantales) Nitriliruptorales Sorokin et al. 2009 (Egicoccales, Salsipaludibacterales) Class Actinomycetia Salam et al. 2020 Acidothermales Sen et al. 2014 Actinomycetales Buchanan 1917 (Aquipuribacterales; Beutenbergiales; Bifidobacteriales; Bogoriellales; Brevibacteriales; Cellulomonadales; Demequinales; Dermabacterales; Dermatophilales; Microbacteriales; Micrococcales; Kineosporiales; Ruaniales) Frankiales Sen et al. 2014 Jiangellales Tang et al. 2015 Longivirga Qu et al. 2018 {S36-B12: CAIYMF01} Motilibacterales Salam et al. 2020 Mycobacteriales Janke 1924 (Corynebacteriales; Actinocatenisporales; Actinoplanetales; Actinopolysporales; Antricoccales; Cryptosporangiales; Geodermatophilales; Glycomycetales; Jatrophihabitantales; Micromonosporales; Nakamurellales; Phytomonosporales; Pseudonocardiales) "Nanopelagicales" Neuenschwander et al. 2018 Propionibacteriales Patrick & McDowell 2015 Sporichthyales Nouioui et al. 2018 Streptomycetales Kampfer 2015 (Catenulisporales, Kitasatosporales) Streptosporangiales Goodfellow 2015
Phylum Bacillota
Class Thermolithobacteria Sokolova et al. 2007 ?Thermolithobacterales Sokolova et al. 2007
Clade "Halanaerobiota" corrig. Alsufyani 2018 (Bacillota_F) Class "Halanaerobiia" Cavalier-Smith 2020 "Anoxybacterales" Pallen, Rodriguez-R & Alikhan 2022 {DY22613} Halanaerobiales corrig. Rainey & Zhilina 1995 Halobacteroidales Chuvochina et al. 2024
Clade Bacillota_G Class "Hydrogenisporia" Pallen, Rodriguez-R & Alikhan 2022 "Capillibacteriales" Pallen, Rodriguez-R & Alikhan 2022 [UBA10575] "Hydrogenisporales" Pallen, Rodriguez-R & Alikhan 2022 [UBA8346] Class Limnochordia Watanabe, Kojima & Fukui 2015 Limnochordales Watanabe, Kojima & Fukui 2015 "Darwinibacterales" corrig. Puchol-Royo et al. 2023
Clade "Selenobacteria" Cavalier-Smith 1992 Class "Selenomonadia" Oren, Parte & Garrity 2016 Acidaminococcales Campbell, Adeolu & Gupta 2015 Anaeromusales Chuvochina et al. 2024 Anaerosinus Strompl et al. 1999 {ICN-92133: ICN-92133} "Azotosporobacter" Xie et al. 2024 {SG130: SG130} "Dendrosporobacterales" Pallen, Rodriguez-R & Alikhan 2022 "Massilibacillaceae" {FLKF01} Pelorhabdus Grässle et al. 2022 {UMGS1260: UMGS1260} "Pelosinaceae" {DSM-13327} Propionisporales Chuvochina et al. 2024 Selenomonadales Marchandin et al. 2010 "Sporomusales" Cavalier-Smith 2006 Veillonellales Campbell, Adeolu & Gupta 2015
Clade "Desulfotomaculota" Watanabe, Fukui & Kuever 2019 (Bacillota_B) Class Peptococcia Chuvochina et al. 2024 Peptococcales Chuvochina et al. 2024 "Thermanaerosceptrales" Pallen, Rodriguez-R & Alikhan 2022 [DRI-13] Class Desulfitisporia Sorokin & Merkel 2023 Desulfitisporales Sorokin & Merkel 2023 Class "Dehalobacteriia" "Avidehalobacterales" Pallen, Rodriguez-R & Alikhan 2022 [UBA4068] "Cryptoclostridiales" Pallen, Rodriguez-R & Alikhan 2022 [UBA7702] "Dehalobacteriales" Class KKC1 Calderihabitantales Chuvochina et al. 2024 Class JADQBR01 "Metallumcola" Hsu et al. 2024 {JADQBR01: JADQBR01} Class DSM-16504 Desulfitibacterales Chuvochina et al. 2024 Class DULZ01 Zhaonellaceae Lv et al. 2020 {DULZ01} Class "Moorellia" Sorokin et al. 2020 Neomoorellales Gtari & Ventura 2025 Class "Thermacetogeniia" corrig. Voyron et al. 2022 Thermacetogeniales Chuvochina et al. 2024 Class Syntrophomonadia Chuvochina et al. 2024 Syntrophomonadales Chuvochina et al. 2024 Class Desulfitobacteriia Chuvochina et al. 2024 Desulfitobacteriales Chuvochina et al. 2024 "Heliobacteriales" Kinman 1994 ex Cavalier-Smith 2020 Class "Carboxydocellia" Pallen, Rodriguez-R & Alikhan 2022 "Carboxydocellales Chuvochina et al. 2024 Class Thermincolia Chuvochina et al. 2024 "Thermincolales Chuvochina et al. 2024