Molecular dialogue between the human gut microbiota and the host: a Lactobacillus and Bifidobacterium perspective

Abstract

The human gut represents a highly complex ecosystem, which is densely colonized by a myriad of microorganisms that influence the physiology, immune function and health status of the host. Among the many members of the human gut microbiota, there are microorganisms that have co-evolved with their host and that are believed to exert health-promoting or probiotic effects. Probiotic bacteria isolated from the gut and other environments are commercially exploited, and although there is a growing list of health benefits provided by the consumption of such probiotics, their precise mechanisms of action have essentially remained elusive. Genomics approaches have provided exciting new opportunities for the identification of probiotic effector molecules that elicit specific responses to influence the physiology and immune function of their human host. In this review, we describe the current understanding of the intriguing relationships that exist between the human gut and key members of the gut microbiota such as bifidobacteria and lactobacilli, discussed here as prototypical groups of probiotic microorganisms.

Prevalence of Antibiotic Resistance Genes among Human Gut-Derived Bifidobacteria

“…Metagenome analysis targeting bifidobacterial AR. Bifidobacteria have predominantly been isolated from the mammalian GIT (23), where their functional contribution in terms of metabolism of various dietary carbohydrates and host glycans has been investigated (11,18,(24)(25)(26). However, their contribution to the resistome of the mammalian gut microbiome has not been studied in any great detail.…”

“…In conclusion, bifidobacteria are dominant members of the infant gut microbiota, and their contribution to host health is well documented (24). Despite many reports investigating the susceptibility of human bifidobacterial species to various antibiotics, very little is known about their resistome.…”

Genomics of the Genus Bifidobacterium Reveals Species-Specific Adaptation to the Glycan-Rich Gut Environment

“…It is expected that metagenomic studies directed to explore the composition of the microbial consortia will discover novel representatives of the Bifidobacterium genus. Despite such findings, many aspects of bifidobacterial biology have yet to be explored (84). This is due to the lack of molecular tools to facilitate efficient exploration of their genetic arsenal, although significant progress has been made in recent years.…”

Genomic Overview and Biological Functions of Exopolysaccharide Biosynthesis in Bifidobacterium spp

“…Lactobacilli, included in the phylum Firmicutes, are non-spore-forming rods or coccobacilli with low GϩC content (Ͻ50%), whereas bifidobacteria are members of Actinobacteria (GϩC Ͼ 50%) and are nonfilamentous rods which can display different morphologies, the bifurcated or "bifido" shape being the most common. Both genera naturally inhabit common ecosystems, such as the oral cavity and the gastrointestinal tract of different animals (15,16). Furthermore, lactobacilli are naturally present in different fermented foods since they are present as contaminants of raw agricultural materials.…”