Fig. 5: MCR-1 prevents PmB-triggered LPS release.

a, Survival of stationary-phase MG1655, MG1655 mcr-1* or MG1655 mcr-1 exposed to 4 µg ml⁻¹ PmB in MM + G, as determined by c.f.u. counts. b, OM disruption of stationary-phase MG1655, MG1655 mcr-1* or MG1655 mcr-1 cells during the first 20 min of exposure to 4 µg ml⁻¹ PmB in MM + G, as determined by uptake of NPN fluorescent dye. c, OM and IM disruption of stationary-phase MG1655, MG1655 mcr-1* or MG1655 mcr-1 exposed to 4 µg ml⁻¹ PmB in MM + G, as determined by uptake of the fluorescent dye SYTOX green. d, Total LPS in stationary-phase MG1655 mcr-1* or MG1655 mcr-1 exposed, or not, to 4 µg ml⁻¹ PmB in MM + G for 15 min. Graph shows quantification of LPS levels from three independent experiments. e, AFM phase images showing stationary-phase MG1655 mcr-1* and MG1655 mcr-1 exposed to 2.5 µg ml⁻¹ PmB in MM + G. The same cell was imaged during the experiment. Scale bar, 250 nm; phase scale (scale inset in second row of image at t = 90 min), 4 deg. f, Mean surface roughness of MG1655 mcr-1* and MG1655 mcr-1 treated with 2.5 µg ml⁻¹ PmB in MM + G. For b and c, the blank value refers to the relevant fluorophore in medium without bacteria. All experiments were replicated in n = 3 independent assays. Error bars show the standard deviation of the mean. Statistical significance of differences was determined by one-way (in d) or two-way repeated measures ANOVA between MG1655 and mcr-1* or mcr-1 (in a, b and c). *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001; NS, not significant.

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