FIG 5 .

Elimination of phagocytosis does not affect killing of Tetrahymena by bacterially produced Stx. Tetrahymena strain NP1 was cocultured with EDL933 or EDL933Δstx at 30°C (black bars) or 37°C (white bars). Cultures were prepared as described in Materials and Methods. Data are expressed as n-fold changes in cell numbers at the end of a 6-h incubation relative to the beginning of the incubation. At the start of the incubation, Tetrahymena cells were present at approximately 10⁴/ml and bacterial cells were present at 10⁸/ml. Error bars represent standard deviations from three or more independent experiments, with each experiment comprising a minimum of three individual measurements. *, P < 0.01; **, P < 0.001.