Bifidobacterium breve UCC2003 Exopolysaccharide Modulates the Early Life Microbiota by Acting as a Potential Dietary Substrate

represents an important early life microbiota member. Specific bifidobacterial components, exopolysaccharides (EPS), positively modulate host responses, with purified EPS also suggested to impact microbe-microbe interactions by acting as a nutrient substrate. Thus, we determined the longitudinal effects of bifidobacterial EPS on microbial communities and metabolite profiles using an infant model colon system. Differential gene expression and growth characteristics were determined for each strain; UCC2003 and corresponding isogenic EPS-deletion mutant ( UCC2003del). Model colon vessels were inoculated with and microbiome dynamics monitored using 16S rRNA sequencing and metabolomics (NMR). Transcriptomics of EPS mutant vs. UCC2003 highlighted discrete differential gene expression (e.g., biosynthetic cluster), though overall growth dynamics between strains were unaffected. The EPS-positive vessel had significant shifts in microbiome and metabolite profiles until study end (405 h); with increases of and , and short-chain fatty acids, with further correlations between taxa and metabolites which were not observed within the EPS-negative vessel. These data indicate that UCC2003 EPS is potentially metabolized by infant microbiota members, leading to differential microbial metabolism and altered metabolite by-products. Overall, these findings may allow development of EPS-specific strategies to promote infant health.