The effect of rifampicin on Mycobacterium smegmatis

Rifampicin was found to inhibit the growth and incorporation of 14C-adenine, 14C-leucine and 14C-glycine in exponentially growing cells of M. smegmatic cultivated in Merrill's synthetic medium. Increasing concentrations of the antibiotic inhibited respiration in resting cells, in the presence of glucose or 2-oxoglutarate as substrates in particular. In addition to the well-known interference of rifampicin with the biosynthesis of RNA, the effect on the energy metabolism should also be considered.