Mycobacterium bovis (M. bovis) is a slow-growing (16- to 20-hour generation time) aerobic bacterium and the causative agent of tuberculosis in cattle (known as bovine TB). It is related to Mycobacterium tuberculosis, the bacterium which causes tuberculosis in humans. M. bovis can jump the species barrier and cause tuberculosis-like infection in humans and other mammals. smegmatis, its non-pathogenic cousin. Although conservation of housekeeping genes and functions is expected, it is generally believed that genes unique to M. tuberculosis might be involved in the expression of its virulence phenotype. Pathways that are conserved in both species could be studied in M. smegmatis to gain insights into specific aspects of physiological adaptation in a considerably shorter time period than is currently possible with M. tuberculosis.As a cause of human disease, M. smegmatis is second to Mycobacterium fortuitum, and can be found in normal human-genital secretions, as well as in lower animals, soil, dust, and water. Disseminated infections caused by M. smegmatis are commonly related to immunosuppression.Mycobacterium smegmatis. Mycobacterium smegmatis is an acid-fast bacterial species in the phylum Actinobacteria and the genus Mycobacterium. It is 3.0 to 5.0 µm long with a bacillus shape and can be stained by Ziehl-Neelsen method and the auramine-rhodamine fluorescent method.Mycobacterium smegmatis is a rapidly growing environmental species not considered a human pathogen. ... The similarity of M. smegmatis to M. fortuitum and the failure to recognize that the former is an environmental species may have contributed to previous failures to recognize it as a human pathogen.