prokaryotes - bacteria see Domain Bacteria Woese et al. 1990 Domain "Bacteria" Woese et al. 1990 Phylum "Firmicutes" corrig. Gibbons and Murray 1978 (Approved Lists 1980) Class Clostridia Rainey 2010 Order Thermoanaerobacterales Wiegel 2010 Family Thermoanaerobacteraceae Wiegel 2010 Genus Thermacetogenium Hattori et al. 2000