The genus Bacterium was a taxon described in 1828 by Christian Gottfried Ehrenberg.[1] The type species was later changed from Bacterium triloculare to Bacterium coli (now Escherichia coli) as it was lost.[2] In 1951 and then in 1954 it was recognised as a nomen generum rejiciendum, which means a generic name to be rejected; this also applied to its family Bacteriaceae.[3][4]
This genus included non-spore forming rods whose relation to other species was obscure (a "taxonomy dumping group"). This is different from the genus Bacillus, whose members were spore forming rods (sensu Cohn 1872[5]).
^Ehrenberg C. G. (1828 [plates], 1831 [text]). Symbolae physicae animalia evertebrata. In: Symbolae physicae, seu Icones adhue ineditae corporum naturalium novorum aut minus cognitorum, quae ex itineribus per Libyam, Aegyptum, Nubiam, Dengalam, Syriam, Arabiam et Habessiniam. Pars Zoologica. Hemprich F. G. & Ehrenberg C. G. (eds.). Officina Academica: Berlin. pp. 2 and 8, plate 2, fig. 6, [1].