Genomic Overview and Biological Functions of Exopolysaccharide Biosynthesis in Bifidobacterium spp

Abstract

bFor many years, bacterial exopolysaccharides (EPS) have received considerable scientific attention, mainly due to their contribution to biofilm formation and, above all, because EPS are potential virulence factors. In recent times, interest in EPS research has enjoyed a welcome boost thanks to the discovery of their ability to mediate communication processes with their surrounding environment and to their contribution to host health maintenance. In this review, we provide a fresh perspective on the genetics and activity of these polymers in members of the Bifidobacterium genus, a common gut inhabitant of humans and animals that has been associated with several health-promoting effects. Bifidobacteria can use EPS to protect themselves against the harsh conditions of the gastrointestinal tract, thus improving their persistence in the host. Indeed, the relevant function of EPS for bifidobacteria is underlined by the fact that most genomes sequenced until now contain genes related to EPS biosynthesis. A high interspecies variability in the number of genes and structural organization is denoted among species/subspecies; thus, eps clusters in this genus do not display a consensus genetic architecture. Their different G؉C content compared to that of the whole genome suggests that eps genes have been acquired by horizontal transfer. From the host perspective, EPS-producing bifidobacteria are able to trigger both innate and adaptive immune responses, and they are able to modulate the composition and activity of the gut microbiota. Thus, these polymers seem to be critical in understanding the physiology of bifidobacteria and their interaction with the host.

Xylella fastidiosa outer membrane vesicles modulate plant colonization by blocking attachment to surfaces

“…Examples of such habitat modification include the production of extracellular polysaccharides that protect cells from predators and from some toxicants to which they might otherwise be exposed and that also retain water (38,39). Likewise, secreted biosurfactants can modulate bacterial motility and modify the chemical environment (40).…”

Genomic Characterization and Transcriptional Studies of the Starch-Utilizing Strain Bifidobacterium adolescentis 22L

“…S5). Notably, the eps2 locus encompasses two genes (BADO_1356 and BADO_1357) predicted to be involved in the biosynthesis of rhamnose (60). Another crucial protein found in the predicted proteome of B. adolescentis 22L sustaining the microbe-host interaction is represented by a serpin homolog (22L_0506), which in B. breve 210B has been shown to counter the adverse effects caused by host proteases and to have a role in modulating inflammation in the human gastrointestinal tract (38).…”

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