Revisiting the Culture of Latent Stage Mycobacterium smegmatis on a Standard Agar Plate

Disc diffusion assay is a basic and initial test in the search for potential inhibitor against bacteria, including high pathogenic bacteria, i.e. Mycobacterium tuberculosis. Mycobacterium smegmatis , due to the characteristics of non-pathogenic, fast growing and can be handled by Biosafety Level 1 facility, is therefore widely used as the replacing model to study M. tuberculosis. However, Mycobacterium spp. can exist in active and latent stage by utilizes different metabolism pathway. Under the circumstances of nutrient or oxygen depletion, Mycobacterium spp. shift the energy generation cycle from tricarboxylic acid cycle (Krebs cycle) to glyoxylate cycle to progress into latent stage. It is challenging to obtain Mycobacterium spp. at latent stage. Here, we revisited the preparation of latent form M. smegmatis . We reported the medium, supplement and inoculum size to produce a reasonable lawn of M. smegmatis in a standard agar plate.