Genus of rod-shaped bacteria that have DNA with a high G+C content and irregular ("coryneform") cell morphology; about 50 species, diverse and contains both aerobes and facultative anaerobes, both mycolate- and non-mycolate-containing species, both tuberculostearic acid- and non-tuberculostearic acid-containing species, and both medically important species and saprophytic, nonpathogenic species.