Mycobacterium dividing. Coloured transmission electron micrograph (TEM) of a Mycobacterium sp. bacterium undergoing binary fission. Binary fission is a type of asexual reproduction that leads to the production of genetically identical offspring, or clones. Mycobacterium are rod-shaped bacteria with a characteristic thick cell wall. Although widespread and usually harmless some species are human pathogens, including M. tuberculosis, which causes tuberculosis, and M. leprae, which causes leprosy.