Figure 5

Membrane damage and cFSE fluorescence leakage in S. thermophilus DSM 20617 T exposed to promysalin, chlorhexidine, and gramicidin. Flow cytometry density diagrams show the cFSE vs PI fluorescence of cells exposed to promysalin or chlorhexidine or gramicidin (100, 200 µg/ml, and 100 µM respectively). (a) Cells before cFDASE labelling. (b) Cell labelled with cFSE and PI. (c) Cells after 60 min exposure to promysalin. Viable cells are gated in G1, viable cells with slightly damaged cell membrane are gated in G2. Dead cells with damaged membrane are gated in G3. The transition of cell population from gate G1 to gate G3 is related to the entity of cell membrane damage. (d) Leakage of cFSE fluorescence outside the cells during the exposure to promysalin, chlorhexidine and the membrane uncoupling gramicidin.