Fig. 2

The effect of NCR peptides and PMB on membrane integrity of S. meliloti. a Outer membrane permeability measured by the fluorescence of NPN at 50 µg/ml (NCR335: 6.4 µM; NCR247: 16.6 µM; NCR001: 9.5 µM) peptide concentrations, and at 12.5 (9 µM) and 50 µg/ml (36 µM) for PMB. b Inner membrane permeability measured by β-galactosidase activity at 50 µg/ml peptide concentrations. c Membrane potential of the S. meliloti cells measured by the red/green fluorescence ration of DiOC₂(3). This dye “exhibits green fluorescence in low concentration in all bacterial cells, however, it accumulates and self-associates in cells that are maintaining a membrane potential resulting in the fluorescence emission to shift from green to red” (Thermo Fisher Scientific)