Bifidobacteria and the infant gut: an example of co-evolution and natural selection

Abstract

Throughout the human life, the gut microbiota interacts with us in a number of different ways, thereby influencing our health status. The acquisition of such an interactive gut microbiota commences at birth. Medical and environmental factors including diet, antibiotic exposure and mode of delivery are major factors that shape the composition of the microbial communities in the infant gut. Among the most abundant members of the infant microbiota are species belonging to the Bifidobacterium genus, which are believed to confer beneficial effects upon their host. Bifidobacteria may be acquired directly from the mother by vertical transmission and their persistence in the infant gut is associated with their saccharolytic activity toward glycans that are abundant in the infant gut. Here, we discuss the establishment of the infant gut microbiota and the contribution of bifidobacteria to this early life microbial consortium.

Keywords: Bifidobacteria; Genomics; Metagenomics; Microbiome; Microbiota.

Fig. 1

Bifidobacterial phylogeny and proven or potential bifidobacterial interactions with its host. A supertree based on the alignment of 413 core COGs was constructed to obtain a robust phylogenetic reconstruction. The bifidobacterial (sub)species are typed with different colours consistent with their ecological origins. Pillars surrounding the tree represent approximate genome sizes. Circles in grey represent relative percentage of genes predicted to be involved in carbohydrate metabolism and transport. The presence of genes encoding various extracellular structures in the bifidobacterial genomes are represented by segments coloured according to the type of structures. Each external sector represents a different extracellular structure (potentially) involved in host interaction. For each extracellular structure, the corresponding image or genetic locus is indicated. The inset of the exopolysaccharide structure represents a cryo-SEM micrograph of a Bifidobacterium animalis subsp. lactis IPLA4549 cell modified as described elsewhere [105]

Fig. 2

Evaluation of bifidobacterial distribution in the human gut as a function of age. Each cake diagram represents the relative abundance of various bifidobacterial (sub)species at the various stages of human life. The relative abundance of the various microbial phyla identified in the human gut at different ages are marked with different colours