[living organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Superkingdom Prokaryota Margulis 1974 nom. nud.
     Kingdom Bacteria Cavalier-Smith 2002 stat. inval. - bacteria see Domain Bacteria Woese et al. 1990 stat. inval.
       Subkingdom Posibacteria Cavalier-Smith 1987 see Domain Bacteria Woese et al. 1990 stat. inval.
         Phylum Firmicutes (Gibbons and Murray 1978) Garrity and Holt 2001 stat. inval. see Phylum Bacillota Gibbons and Murray 2021
           1 Class Bacilli Ludwig et al. 2010
           2 Class Clostridia Rainey 2010
           3 Class Erysipelotrichia Ludwig et al. 2010 [monotypic]
           4 Class Negativicutes Marchandin et al. 2010 [monotypic]
           5 Class Thermolithobacteria Sokolova et al. 2007 [monotypic]