Abstract
BackgroundBifidobacteria are commensal microbes of the mammalian gastrointestinal tract. In this study, we aimed to identify the intestinal colonization mechanisms and key metabolic pathways implemented by Bifidobacterium dentium.ResultsB. dentium displayed acid resistance, with high viability over a pH range from 4 to 7; findings that correlated to the expression of Na+/H+ antiporters within the B. dentium genome. B. dentium was found to adhere to human MUC2+ mucus and harbor mucin-binding proteins. Using microbial phenotyping microarrays and fully-defined media, we demonstrated that in the absence of glucose, B. dentium could metabolize a variety of nutrient sources. Many of these nutrient sources were plant-based, suggesting that B. dentium can consume dietary substances. In contrast to other bifidobacteria, B. dentium was largely unable to grow on compounds found in human mucus; a finding that was supported by its glycosyl hydrolase (GH) profile. Of the proteins identified in B. dentium by proteomic analysis, a large cohort of proteins were associated with diverse metabolic pathways, indicating metabolic plasticity which supports colonization of the dynamic gastrointestinal environment.ConclusionsTaken together, we conclude that B. dentium is well adapted for commensalism in the gastrointestinal tract.
Highlights
Bifidobacteria are important members of the Actinobacteria phylum within the human intestinal microbiota [1,2,3,4,5,6,7,8,9,10]
We have previously demonstrated that B. dentium colonizes gnotobiotic mice, promotes goblet cell maturation, secretion of the mucin protein MUC2, stimulates intestinal serotonin production, generates the neurotransmitter γ-aminobutyric acid (GABA), alleviates visceral hypersensitivity and regulates the gut-brain-axis [21,22,23, 38, 42]
B. dentium is acid resistant and can adhere to intestinal mucus suggesting its efficacy to persist in the gastrointestinal tract To colonize the gastrointestinal tract microbes must overcome the acidic pH found in the stomach and upper GI to gain access to the lower parts of the intestine
Summary
Bifidobacteria are important members of the Actinobacteria phylum within the human intestinal microbiota [1,2,3,4,5,6,7,8,9,10]. The establishment of bifidobacteria in the intestine is connected with beneficial health effects, including immune development, neuromodulation, inhibition of pathogens, and modulation of the intestinal microbiota composition [11,12,13,14,15,16,17,18,19,20,21,22,23]. To produce these beneficial effects, bifidobacteria must be able to survive gastrointestinal (GI) transit and Nutrient availability and utilization shapes the composition and gene expression of the intestinal microbiota [11, 24,25,26,27,28,29,30]. We aimed to identify the intestinal colonization mechanisms and key metabolic pathways implemented by Bifidobacterium dentium
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