Figure 1From: Real-time detection of viable microorganisms by intracellular phototautomerismConceptual drawing of the RTV assay principle. Live and dead cells are exposed to a probe in a low pH environment. The probe enters both cell types, but only emits a fluorescence signal in live cells which have maintained their neutral, intracellular pH. The pH in dead cells reflects the extracellular acidic conditions leading to signal suppression.Back to article page