The GIT competition assay was performed using the same component assay as previously described. Test organisms L. monocytogenes ATCC15313, L. innocua ATCC33090, were grown in 100 mL BHI broth at 37 °C for 18 h. Antagonistic strains, Ent. faecium strains ST651ea, ST7119ea, and ST7319ea, on the other hand, were grown in MRS broth. Before performing the assays, bacterial cells from all the above strains were all adjusted to obtain OD600 = 0.5 to standardize the cell concentrations used in the experiments. Each test organism was measured against all bacteriocinogenic strains being evaluated for their safety. Serial dilutions of adjusted bacterial suspensions were plated using respective growth media for determining the initial viable cell population (CFU/mL). The obtained counts are designated as t0.
Following the same assay for the gastric pass and duodenum pass simulations, all antagonistic set-ups with the test organisms L. monocytogenes ATCC15313 and L. innocua ATCC33090 were plated in Listeria selective medium (RAPID’L.mono Medium, BioRad, Hercules, CA, USA). All plates were incubated for 72 h at 37 °C before viable cell counting. Calculations for survival rate were carried out as previously described. All experiments were performed in at least three independent experiments comprising three replicates for each set-up.
Following the same assay for the gastric pass and duodenum pass simulations, all antagonistic set-ups with the test organisms L. monocytogenes ATCC15313 and L. innocua ATCC33090 were plated in Listeria selective medium (RAPID’L.mono Medium, BioRad, Hercules, CA, USA). All plates were incubated for 72 h at 37 °C before viable cell counting. Calculations for survival rate were carried out as previously described. All experiments were performed in at least three independent experiments comprising three replicates for each set-up.