Figure 6

Invasiveness of L. monocytogenes after acid shock at 25°C. Invasion assays were performed with Caco-2 cells. Untreated and acid-shocked EGDe cells were used for infection at an MOI of 10. The invasion process was blocked after 1 h by cell washing and gentamycin treatment, and the epithelial cells were lysed to enumerate intracellular listeriae. The percentage of colony forming units (cfu) derived from acid treated inoculate as normalized to the control using untreated cells. Standard deviations of three independent invasion assays, performed at least as triplicates, are shown. In each experiment, the significance value was below 0.05 (p < 0.05) as calculated by the Student’s t-test. The fold difference in invasion is approximately 6-fold at 30 min and 12-fold at 60 min after acid shock.