Methods Bacterial strains Lactobacillus plantarum MB452 [47] was isolated from VSL#3 (Orphan Australia Pty Ltd, Berwick, Australia). Selleckchem Decitabine A sachet of VSL#3 powder was suspended in 50 mL of sterile water and the culture was streaked on MRS agar plates (de Man, Rogosa and Sharpe Broth, Difco, Sparks, USA) and incubated aerobically at 30°C, 37°C and 42°C and anaerobically at 37°C. Colony morphologies were recorded and sample colonies from each plate were sub-cultured into Brain Heart Infusion broth (Difco, USA) with 30% glycerol for storage at -85°C. As described in Additional File 2, colonies with similar morphology were compared using pulse-field gel electrophoresis and

representatives of each profile were identified based on their 16 s rRNA sequences. Mammalian cell culture Caco-2 cell (HTB-37; ATCC) stock cultures were grown in T75 flasks in M199 tissue culture medium with 10% foetal bovine serum (GIBCO, Invitrogen Corporation, Auckland, NZ), 1% non-essential amino acids (MEM non-essential amino acids 100× solution, Sigma-Aldrich, St Louis, USA) and 1% penicillin-streptomycin

(10,000 units penicillin G sodium salt and 10000 g streptomycin sulphate in 0.85% saline, GIBCO, Invitrogen Corporation, Auckland, NZ) at 37 C in 5% CO2. The media was replaced every 3 to 4 days and the cells were subcultured weekly at a ratio of 1:3. Caco-2 cells with a passage number of 30 to 35 were used for all experiments. Trans-epithelial electrical resistance assay Caco-2 cells were seeded onto 14 mm collagen membrane inserts (Cellagen™ Discs CD-24, PAK6 selleck chemicals MP Biomedicals, Ohio, USA) at a density of 105 cells/insert. Each insert was placed in a well in a 12-well plate with 1 mL of media in the bottom and 250 µL media in the top. The media was replaced every 2 to 3 days. Confluent Caco-2 monolayers (5 days old) were used for the majority of the TEER experiments; except for the TEER experiment done in parallel with the gene expression experiment where differentiated Caco-2 monolayers were used (18 days old). All Caco-2 monolayers had initial TEER values of greater than 300

ohms.cm2. The Caco-2 monolayers were prepared the day before the TEER assay by removing the media, washing three times with PBS and adding M199 with 1% non-essential amino acids (without foetal bovine serum and penicillin-streptomycin) to ensure growth of the bacterial cells. To prepare the bacteria for the TEER assay, an overnight culture of bacterial cells (MRS broth, 37°C, 5% CO2) were collected by centrifugation (12,000 rpm for 5 minutes in a micro centrifuge), washed in phosphate buffered saline (PBS, pH 7.2), and suspended in M199 with 1% non-essential amino acids to the required optical density at 600 nm. After the initial resistance readings were taken on the day of the experiment, the media was removed from the top of the Caco-2 monolayers and replaced with the treatment solutions.