FIG 10.

Strain competition in broth culture. (A) Phage life cycle. (Top) Lytic infection results in phage production and bacterial death; (bottom) the repressor produced by lysogenic phage can prevent lytic infection and bacterial death. (B to F) LB broth or filter-sterilized culture supernatant was inoculated with 10³ CFU of a single strain or strains mixed 1:1, as indicated, and the numbers of CFU were assessed over time. (B) LB broth was inoculated with Nissle, EHEC, or both. The growth of Nissle was suppressed by EHEC. (C) Nissle was inoculated into LB broth. Nissle and a colony of Nissle that survived coculture with EHEC (Nissle::Stx2PT) were inoculated into the culture supernatant from EHEC. The growth of Nissle was suppressed by the EHEC supernatant. (D) Nissle was inoculated into LB broth or the supernatant from Nissle::Stx2PT. The growth of Nissle was suppressed by the Nissle::Stx2PT supernatant. (E) LB broth was inoculated with Nissle, EDL933, or both. The growth of neither strain was suppressed in mixed culture. (F) LB broth was inoculated with Nissle, UPEC, or both. The growth of neither strain was suppressed in mixed culture.