Abstract
Consumption of fermentable dietary fibers (DFs), which can induce growth and/or activity of specific beneficial populations, is suggested a promising strategy to modulate the gut microbiota and restore health in microbiota-linked diseases. Until today, inulin and fructo-oligosaccharides (FOS) are the best studied DFs, while little is known about the gut microbiota-modulating effects of β-glucan, α-galactooligosaccharide (α-GOS) and xylo-oligosaccharide (XOS). Here, we used three continuous in vitro fermentation PolyFermS model to study the modulating effect of these DFs on two distinct human adult proximal colon microbiota, independently from the host. Supplementation of DFs, equivalent to a 9 g daily intake, induced a consistent metabolic response depending on the donor microbiota. Irrespective to the DF supplemented, the Bacteroidaceae-Ruminococcaceae dominated microbiota produced more butyrate (up to 96%), while the Prevotellaceae-Ruminococcaceae dominated microbiota produced more propionate (up to 40%). Changes in abundance of specific bacterial taxa upon DF supplementation explained the observed changes in short-chain fatty acid profiles. Our data suggest that the metabolic profile of SCFA profile may be the most suitable and robust read-out to characterize microbiota-modulating effects of a DF and highlights importance to understand the inter-individual response to a prebiotic treatment for mechanistic understanding and human application.
Highlights
The human gut microbiota is composed of around 1014 bacterial cells that belong to more than 1000 species[1], dominated by members belonging to the two phyla, Firmicutes and Bacteroidetes[1,2]
The microbiota composition of both donors was representative for a healthy human microbiota (Supplementary Table S2), with Firmicutes (D3: 51%; D4: 57%) and Bacteroidetes (D3: 26%; D4: 32%) as the dominant bacterial phyla
In this study the effect of supplementation of four different dietary fibers on human gut microbiota was investigated at the levels of metabolic and bacterial composition using a continuous in vitro fermentation system, modeling adult proximal colon conditions
Summary
The human gut microbiota is composed of around 1014 bacterial cells that belong to more than 1000 species[1], dominated by members belonging to the two phyla, Firmicutes and Bacteroidetes[1,2]. Baseline bacterial composition of the host microbiome has repeatedly been observed to be a key factor to explain responses of the gut microbiota to different dietary interventions[10,11,12]. In vitro fermentation models are powerful approaches to investigate gut microbiota functionality without host effects in a highly controlled environment[29] These models allow the strict control of physiologic parameters, such as retention time, pH, temperature and anaerobiosis, and medium composition used to mimic the diet. Continuous fermentation systems with immobilized gut microbiota were shown to simulate the high-cell density, biodiversity and long-term stability of the intestinal microbiota[32] This prevents washout of less competitive bacteria and ensures the repeated exposure of a single microbiota to different fibers[29,30,32]. The PolyFermS model allows the parallel testing of different treatments on singular microbiota
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