Microbial analysis using Sharma's reaction

The photoreaction of thionine with NAD(P)H leads to the formation of non-fluorescent semi and lecuothionine. This has been previously used for the development of enzymatic assays. We show that the fluorescence of thionine is quenched in the presence of Nocardia corallin. We ascribe this decrease in fluorescence to the presence of NAD(P)H present on the walls and in the body of the cells as described by Sharma. We therefore demonstrate that it is possible to measure, in situ, NAD(P)H in Nocardia corallin in a simple and inexpensive manner and that this finding extends the analytical application of Sharma's reaction to other organisms.