mycobacterium smegmatis mycobacterium smegmatis mycobacterium smegmatis is an acid-fast bacterial species in the phylum actinomycetota 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. it was first reported in november 1884 by lustgarten, who found a bacillus with the staining appearance of tubercle bacilli in syphilitic chancres. subsequent to this, alvarez and tavel found organisms similar to that described by lustgarten also in normal genital secretions (smegma). this organism was later named m. smegmatis. mycobacterium smegmatis scientific classification domain: bacteria phylum: actinomycetota class: actinomycetia order: mycobacteriales family: mycobacteriaceae genus: mycobacterium species: m. smegmatis binomial name mycobacterium smegmatis(trevisan 1889)lehmann & neumann 1899 some species of the genus mycobacterium have recently been renamed to mycolicibacterium, so that m. smegmatis is now mycolicibacterium smegmatis. m. smegmatis, which was previously considered a nonmotile organism, uses a sliding mechanism that allows it to move around its environment. henrichsen defines it as, “a kind of surface translocation produced by the expansive forces in a growing culture in combination with special surface properties of the cells resulting in reduced friction between cell and substrate”. essentially, the bacteria form a single-layered sheet and are able to move slowly together without the use of any extracellular structures, like flagella or pili. although it hasn’t been determined exactly how this mechanism works, the surface properties of the unique cell wall (figure 1) of m. smegmatis have been found to play a role. for example, this sliding ability is correlated with the presence of glycopeptidolipids (glps) on the outermost part of the cell wall. glps are amphiphilic molecules that could potentially decrease surface interactions or create a conditioning film that allows movement. although the exact role of glps in sliding is not known, without them m. smegmatis does not have the ability to translocate. plaques from a virus isolated from a compost heap near ucla. the bacterium is m. smegmatis virulence m. smegmatis is generally considered a non-pathogenic microorganism; however, in some very rare cases, it may cause disease. use in research mycobacterium smegmatis is useful for the research analysis of other mycobacteria species in laboratory experiments. m. smegmatis is commonly used in work on the mycobacterium genus due to it being a "fast grower" and non-pathogenic. m. smegmatis is a simple model that is easy to work with, i.e., with a fast doubling time and only requires a biosafety level 1 laboratory. the time and heavy infrastructure needed to work with pathogenic species prompted researchers to use m. smegmatis as a model for mycobacterial species. mycobacterium smegmatis shares the same peculiar cell wall structure of m. tuberculosis and other mycobacterial species. it is also capable of oxidizing carbon monoxide aerobically, as is m. tuberculosis. bacterial secretion systems are specialized protein complexes and pathways that allow bacterial pathogens to secrete proteins across their cell membranes and, ultimately, to host cells. these effector proteins are important virulence factors, which allow the pathogen to survive inside of the host. there are many different kinds of specific secretion systems, and m. tuberculosis has an snm (secretion in mycobacteria) protein secretion system. although the snm secretion system is a key in determining m. tuberculosis virulence, all mycobacteria have genes encoding the components of this system. this area of the genome is referred to as the rd1 locus. m. smegmatis is commonly used to study snm secretion because of its genetic similarities and analogous function to m. tuberculosis, as well as ease of growing in the lab. one example of how this can be applied in research is the identification of gene products required for snm secretion. by knocking out genes in the rd1 locus of m. smegmatis and testing efficiency of snm secretion before and after gene knockout, specific genes can be identified as necessary for snm secretion. these findings can be applied to the snm secretion system of m. tuberculosis. mycobacterium smegmatis is readily cultivatable in most synthetic or complex laboratory media, where it can form visible colonies in 3–5 days. these properties make it a very attractive model organism for m. tuberculosis and other mycobacterial pathogens. m. smegmatis mc2155 is also used for the cultivation of mycobacteriophage. production of electricity