Figure 6

PLNC8 αβ damages the integrity of bacterial cell wall and cell membrane. (A) The uptake of Sytox Green by S. epidermidis ATCC 12228 after exposure for 5 min to different peptide combinations (25 µM, except for PLNC8 αβ where two concentrations were used, 12.5 µM and 25 µM), indicates damaged cell membrane, scale bar is 300 µm. Visualization of bacterial damage with transmission electron microscopy. The cell membrane (CM) was completely detached (red arrow heads) and leakage of intracellular content is observed (black arrow heads). The thickness of the cell wall (CW) was increased (blue arrow heads). Scale bar is 200 nm. Scanning electron microscopy demonstrates further the substantial amounts of leaked material from the bacteria, particularly by PLNC8 α, while PLNC8 β and the combination of both peptides results in bacterial lysis. Scale bar is 100 nm. (B) Quantification of the fluorescence intensity of Sytox Green. (C) Quantification of the thickness of the cell wall. (D) Quantification of the area covered by bacteria and leaked material.