These aerobic spore-forming actinomycetes produce a branched vegetative mycelium bearing aerial hyphae. Chemoorganotrophs. The cell wall contains meso-diaminopimelic acid but no characteristic sugars or other amino acids. Mycolic acids are absent. Menaqui-nones typically contain 9 or 10 isoprene units (MK-9,MK-10). The spore arrangement and morphology are distinctive for each genus and provide the means of differentiating genera within this group.