The forgotten Canetti: Mycobacterium canettii and the origins of tuberculosis

Within the genus Mycobacterium, a diverse group of aerobic, non-motile and rod-shaped bacteria that possess a cell wall rich in mycolic acids, there is an often disregarded member which, however, is thought to represent the closest known lineage to the ancestor of the Mycobacterium tuberculosis complex (MTBC): Mycobacterium canettii [1,2]. This tubercle bacillus shares 98%-99.9% of genome sequence identity with members of the MTBC, which exceeds the 95% threshold to be considered the same species.