Bacterial membrane potential analyzed by spectrofluorocytometry

Cells ofMycobacterium smegmatis 607 in their late exponential growth were stained with rhodamine 123. The stained bacterial populations were analyzed by fluorocytometry and spectrofluorometry. Responses of the bacterial membrane potential to agents such as valinomycin, graimicidin, nigericin, and sodium azide were analyzed with the two techniques mentioned above. The results have shown that the flow cytometric technique allowed detection of changes in bacterial membrane potential and allowed population response analysis to ionophore activity. The applications of this technique are promising for the rapid detection of membrane potential mutants and for the estimation of the viability of a bacterial population.