Trackability of proteins from probiotic Bifidobacterium spp. in the gut using metaproteomics.

Beneficial effects of Bifidobacterium spp. on gut microbiota development and infant health have been reported earlier. Therefore, supplementation of infant formulas with probiotic bifidobacteria, as well as prebiotics stimulating bifidobacterial growth, has been proposed. Here, we studied the faecal microbiome of infants supplemented with specialized nutrition, of which some received a standard amino acid-based formula (AAF) and others an AAF with a specific mixture of prebiotics and a probiotic (synbiotics) using metaproteomics and 16S rRNA gene sequencing. Faecal samples were taken at baseline, as well as after 6 and 12 months fed with the specialized formula. The aim was to compare microbial differences between infants treated with the standard AAF and those who received the additional synbiotics. Our findings show that infants who received AAF with synbiotics have significantly higher levels of Bifidobacteriaceae DNA as well as significantly increased levels of Coriobacteriaceae proteins, over time. Moreover, at visit 12 months higher levels of some bifidobacterial carbohydrate-active enzymes, known to metabolize oligosaccharides, were observed in the synbiotic group compared to the non-synbiotic group. The results indicate that the synbiotics provided in our study are trackable in faecal samples on the DNA and protein level during the intervention period.

Cross-feeding between Bifidobacterium infantis and Anaerostipes caccae on lactose and human milk oligosaccharides.

The establishment of the gut microbiota immediately after birth is a dynamic process that may impact lifelong health. At this important developmental stage in early life, human milk oligosaccharides (HMOs) serve as specific substrates to shape the gut microbiota of the nursling. The well-orchestrated transition is important as an aberrant microbial composition and bacterial-derived metabolites are associated with colicky symptoms and atopic diseases in infants. Here, we study the trophic interactions between an HMO-degrader, Bifidobacterium infantis and the butyrogenic Anaerostipes caccae using carbohydrate substrates that are relevant in the early life period including lactose and total human milk carbohydrates. Mono- and co-cultures of these bacterial species were grown at pH 6.5 in anaerobic bioreactors supplemented with lactose or total human milk carbohydrates. A. caccae was not able to grow on these substrates except when grown in co-culture with B. infantis, leading to growth and concomitant butyrate production. Two levels of cross-feeding were observed, in which A. caccae utilised the liberated monosaccharides as well as lactate and acetate produced by B. infantis. This microbial cross-feeding points towards the key ecological role of bifidobacteria in providing substrates for other important species that will colonise the infant gut. The progressive shift of the gut microbiota composition that contributes to the gradual production of butyrate could be important for host-microbial crosstalk and gut maturation.