Fig. 2: Changes in drug efficacy against sensitive Escherichia coli Wyl are consistent with theoretical predictions.

A, B Change in normalised density of Escherichia coli Wyl as a function of tetracycline concentration, when Wyl grows in mixed culture with tetracycline-sensitive Salmonella typhimurium (A) and tetracycline-resistant Escherichia coli GB(c) (B). The change in density of Wyl growing in mixed culture is shown in black, with grey showing the change in density in pure culture. The IC₉₀ in each condition is shown as dots, red for mixed culture conditions and dark grey for pure culture, connected by a dotted line. Non-parametric, Mann–Whitney U-test between IC₉₀s is shown in the inset. Raw data is shown as dots, whereas the boxes represent median (centre of the box), 25th, and 75th percentile of the dataset. The whiskers show the most extreme data points that are not outliers. C Theoretical change in S₁-cell density with increasing antibiotic concentration in pure (grey) and mixed (black) culture conditions with neighbours that have different drug sensitivity. The plot represents the case where both species have different carbon uptake (\(\bar \mu\)_j), and differences in IC₉₀ are represented as shown in (A, B) for consistency. Insets in (A and B), and raw data for relative drug content can be found in Fig. S4.