Fig. 3.

Evolution by phage-mediated HGT is adaptive. (A) The ancestral, evolved, and resident clones were tested for phage-mediated lysis. The evolved clones include 3 different genetic backgrounds: Nef, KingRac, and Nef+KingRac prophages without any other mutations. Drops (10 µL) of phage-containing supernatant (phage lysate) were applied to growing bacterial cell lawns of each clone. The phage lysate was obtained from the clones' supernatant after mitomycin C induction (5 µg/mL). The KingRac clone is poorly induced (Fig. 2B), and the number of phage particles is expected to be small. ND, not determined. For the other clones, the exact number of phage particles is unknown, as individual phage plaques could not be scored, preventing comparison of the infection efficiency between different phage lysates. (B and C) The ancestral, evolved (Nef, KingRac, and Nef+KingRac), and resident clones were grown in intestinal medium. The maximum growth rate (±2 SE) was assessed in small and large intestinal medium (n = 3) (B), and the yield (±2 SE) after 24 h of growth in small and large intestinal medium (n = 3) was measured (C). (D and E) The ancestral and evolved (Nef, KingRac, and Nef+KingRac) clones were grown in minimal medium supplemented with mannose or gluconate (0.03%). The maximum growth rate (per hour) was assessed in mannose or gluconate medium (n = 5) (D), and the yield after 24 h of growth in mannose or gluconate medium (n = 5) was measured (E).