Fig. 3: Environment dilution can control relative strain fitness.

a Analysis of the mathematical model with varying dilution rate. Solid black lines show the stable steady states (extinction of one or other strain), the dashed black line indicates an unstable steady state. The arrows show the direction of population change on either side of the unstable manifold. b Dilution rate is approximated by varying the initial density of the co-cultures in the microtitre plate; lower initial density approximating faster dilution rates. We observe the same switch, from competitive exclusion to bacteriocin killing, predicted by the model. c The “winning” strain after 5 h of growth in co-culture, over a range of initial population ratios, mimics the model prediction. In b the lines show the mean of the rolling mean (centred window size = 3) and the shaded ribbons show the standard deviation of three replicates. In c, each shaded rectangle shows the mean proportional population change of three replicates, calculated at 5 h post-inoculation.