To evaluate a direct antimicrobial effect of Lactobacillus strainsagainst GBS, ‘inhibition’ experiments were carried out incubating1 × 108 Lactobacillus cells or the corresponding supernatants with thesame amounts of Streptococcus cells (ratio 1:1).In details, 1 × 108 Streptococcus cells (200 μL of a PBS stock solutionwith a concentration of 5 × 108 CFU/mL) were pelleted and the supernatant was discarded. Afterwards, 200 μL of the stock suspensions ofLactobacillus cells or CFS were added and the mixes were incubated for 60 min at 37 °C. At the end of the incubation, the tubes were centrifuged at 20,000×g for 10 min. Pellets were re-suspended in PBS,serially-diluted, and 10 μL of the suspensions were seeded on blood agarplates. After 24 h of aerobic incubation at 37 °C, GBS colonies werevisually counted and expressed as number of Streptococcus cells/mL.Each experiment was conducted in duplicate and a control tube(1 × 108 Streptococcus cells incubated with 200 μL of PBS or MRS,without Lactobacillus cells and supernatants) was always included.Results were expressed as the percentage of the average number ofStreptococcus cells/mL. The GBS growth in the presence of Lactobacilluscells or CSF was compared with the corresponding control (GBS growthin the absence of Lactobacillus cells and supernatants), taken as 100%.Lactobacillus cells were re-cultured in MRS plates to evaluate theirviability after being employed in the ‘inhibition’ experiments.