Microscopic images of the Synechocystis samples. Details of sample images for the examined Synechocystis samples with a different number of viable cells (A: 100%, B: 75%, C: 50%, D: 25%, E: 0%). All images show an overlay of microscopic fluorescent and phase contrast pictures. Red fluorescence is caused by chlorophyll and represents viable cells. Non-viable cells show a green unspecific autofluorescence.