Fig. 4.

Effects of sub-MIC_R streptomycin treatment on PA01:Rms149 resistant cell dynamics. (A) Proportion of dead cells after 7 h in sub-MIC_R streptomycin. The proportion of dead cells in streptomycin-treated cultures was estimated using live–dead staining and flow cytometry. Points represent six independent treatment replicates at each concentration, and line segments indicate their mean. Differences from the streptomycin-free control cultures were assessed using a one-way ANOVA followed by a post hoc Dunnett’s test (n.s.: not significant, P > 0.05; *P = 9e-3; **P < 1e-4). Effects identified as significant do not change if we exclude an outlier replicate (shaded-in points) showing consistently elevated dead cell fractions (SI Appendix, Table S3). (B) Viable cell population dynamics in sub-MIC_R streptomycin. Points with connecting lines indicate the mean number of viable cells across 6 replicate cultures per streptomycin concentration, per sampling time point (or 12 replicates for streptomycin-free controls); the error bars indicate SE. SI Appendix, Fig. S7 shows all individual replicates. Viable cell numbers were estimated by plating undiluted culture samples; plots are truncated when colonies became too dense to count. Significance of each streptomycin concentration compared to the streptomycin-free control was assessed by a post hoc Dunnett’s test (n.s.: not significant, P = 0.87; *P = 4e-4; **P < 1e-4).