Mean (± standard deviation) microbial metabolic activity in terms of gas production (kPa) (A) and pH decrease (upH) (B) upon a 48 h fermentation of 5 g/L BMOS containing 1.5 × 107 CFU/mL of B. lactis previously grown on either Dextrose (Pre-Dextrose Bl + BMOS, n = 3) or BMOS (Pre-BMOS Bl + BMOS, n = 3), by the infant fecal microbiota of Donors 1 and 8, versus their respective controls (Control, Pre-Dextrose Bl and Pre-BMOS Bl, n = 3). Significant differences between the different formulations within each donor are indicated with different letters (a, b, c, d), as tested with a one-way ANOVA with Tukey’s HSD post hoc test (p < 0.05). In contrast, when at least one letter is shared between two treatments, there was no significant difference between these groups.