Gram-positive, nonmotile, moderately-long to long, and acid-fast rods. Colony characteristics It forms smooth to rough colonies after 7 or more days of incubation and is considered a slow grower. Colonies grown in dark are nonpigmented, when grown in light or when young colonies are exposed briefly to light, colonies become brilliant yellow (photochromogenic) according to the Runyon classification of Non-Tuberculous Mycobacteria. If grown in a lighted incubator, most strains form dark red crystals of β-carotene on the surface and inside of colony. Physiology Its physiology is described as growth on Middlebrook 7H10 agar at 37°C within 7 days or more, resistant to pyrazinamide and susceptible to ethambutol. Differential characteristics It is closely related to the non-pathogenic, also slowly growing, nonpigmented, M. gastri. Both species share an identical 16S rDNA but differentiation is possible by differences in the ITS and hsp65 sequences. A commercial hybridisation assay (AccuProbe) to identify<unk>  exists.<unk>  complex Several former subtypes of<unk>  have been reclassified as closely related species, and along with M. gastri form the<unk>  complex (MKC). The species in the MKC are *<unk>  (former subtype I) * Mycobacterium persicum (former subtype II) * Mycobacterium pseudokansasii (former subtype III) * Mycobacterium ostraviense (former subtype IV) * Mycobacterium innocens (former subtype V) * Mycobacterium attenuatum (former subtype VI) * and Mycobacterium gastri
Mycobacterium kansasii
Mycobacterium africanum
Mycobacterium tuberculosis
Mycobacterium canetti
Mycobacterium haemophilum
Mycobacterium orygis
Mycoplasma incognitus
Bacillus anthracis