Fig 1.

Bacterial density and resistance to bacteriophages. (a to c) Density of bacteria in populations treated with single phages, pairs of phages either sequentially (filled circles) or simultaneously (open circles), or all four phages sequentially (filled circles) or simultaneously (open circles). Density is shown as means ± SE for 16 replicate selection lines (four at each dilution factor) after 12 experimental transfers. (d to f) Resistance to selective phages, calculated as the proportion of infection assays that showed no evidence of inhibition by the phages to which bacteria were exposed over the phage therapy experiment; points show means ± SE from four replicates in each treatment. (g and h) Total resistance, measured against all four phages; points show means ± SE for four replicate populations; scores for total resistance in the all-phage treatments are not shown because they are identical to those for resistance to selective phages.