FIG 3.

Live-cell status of E. coli O157:H7 and E. coli O104:H4 under raw sausage conditions of decreased pH and the presence of sodium nitrite in vitro. Assays were performed either in Trypticase soy broth plus 0.5% yeast extract (TSBY) as a control, in TSBY adjusted to pH 5.1 with 20% (vol/vol) lactic acid (TSBY pH 5.1), or in TSBY at pH 5.1 with the addition of 150 mg/liter sodium nitrite (TSBY pH 5.1, 150 ppm NaNO₂). After 0, 18, 42, and 66 h of incubation at 22°C, cell viabilities were assessed using the LIVE/DEAD BacLight viability kit according to the manufacturer's instructions. The numbers of dead, viable, and damaged cells were determined by counting red, green, and orange cells in a triplicate setup, and the percentages of live, dead, and damaged cells were calculated. Values are averages for three independent experiments. *, P < 0.05.