The TEER was calculated from the resistance using Eqn.(1), where the background resistance was 14 Ω and the membrane area was 1.54 cm2. The change in TEER for each insert was calculated using Eqn.(2). Treatments were compared in genstat (version 11) using residual maximum likelihood (REML) analysis with an unstructured covariance model to take into account the repeated measures. (1) Bacterial cultures were grown overnight in MRS broth at 37 °C with 5% CO2. Each culture was vortexed, and separate 10-mL aliquots were collected by centrifugation (3800 g for 20 min). Cell pellets were suspended to

an approximate cell concentration of 108–1010 CFU mL−1 in the following test solutions: MRS broth control, MRS broth adjusted to pH 2.0, MRS broth adjusted to pH 4.0, 0.5% w/v bile and 1% w/v bile. The time points (2 and 4 h) were chosen to represent the time it takes to pass through the human upper see more gastrointestinal system to the lower intestinal tract. The concentrations of bile (0.5% and 1%) and pH values (pH 2.0 and 4.0) were chosen to represent the range of these variables found in the human stomach. Bacterial viability was assessed after 2 and 4 h with triplicate 20-μL dilution spots on Z-VAD-FMK datasheet Luria–Bertani

(LB) agar plates. Values were log-transformed before REML analysis using an unstructured covariance model. Quantitative analysis of bacterial adherence to both confluent undifferentiated (5 days) and differentiated (18 days) Caco-2 cells was tested as described previously (Donnenberg & Nataro, 1995). Bacterial strains were grown overnight in MRS broth and approximately 107 CFU (10 μL) were added to each well, with each strain being assessed for Exoribonuclease adherence (3 and 6 h) in triplicate. Lactobacilli were enumerated on LB agar plates as described previously. Values were log-transformed

before anova analysis. The effect of coculture of L. plantarum DSM 2648 and EPEC O127:H6 (E2348/69) was examined in both the TEER and the cell adherence assay. The TEER assay was performed with two hourly readings for 10 h as described previously with overnight cultures of L. plantarum DSM 2648 prepared from MRS broths. The EPEC strain was grown aerobically overnight at 37 °C in LB broth, with shaking at 100 r.p.m. EPEC cells were collected by centrifugation (20 000 g for 5 min) and suspended in M199 with 1% v/v nonessential amino acids to an OD600 nm of 0.1. TEER coculture experiments also included both bacterial strains individually to assess separate effects for control purposes. For adherence to Caco-2 cell monolayers, both the L. plantarum DSM 2648 and the EPEC strain were grown in MRS and LB broth and inoculated into tissue culture wells containing undifferentiated Caco-2 cells as described previously. The EPEC strain was incubated alone or simultaneously cocultured with L. plantarum DSM 2648 for 3 or 6 h. The effects of a 3-h preincubation of L.