Recently, the concept of prebiotics has been revisited to expand beyond non-digestible oligosaccharides, and the requirements for selective stimulation were extended to include microbial groups other than, and additional to, bifidobacteria and lactobacilli. Here, the gut microbiota-modulating effects of well-known and novel prebiotics were studied. An in vitro fermentation screening platform (i-screen) was inoculated with adult fecal microbiota, exposed to different dietary fibers that had a range of concentrations (inulin, alpha-linked galacto-oligosaccharides (alpha-GOS), beta-linked GOS, xylo-oligosaccharides (XOS) from corn cobs and high-fiber sugar cane, and beta-glucan from oats), and compared to a positive fructo-oligosaccharide (FOS) control and a negative control (no fiber addition). All dietary fibers displayed prebiotic activity, with beta-glucan showing more distinct effects on the microbial composition and metabolism compared to the other fibers. Beta-glucan induced the growth of Prevotella and Roseburia with a concomitant increase in propionate production. Inulin and both forms of GOS and XOS had a strong bifidogenic effect on the microbial composition. A dose-response effect was observed for butyrate when exposed to beta-glucan and inulin. The findings of this study support the potential for alpha-GOS, XOS, and oat beta-glucan to serve as novel prebiotics, due to their association with the positive shifts in microbiome composition and short-chain fatty acid production that point to potential health benefits.

The objective of the current study was to evaluate the potential of 2′-FL and GOS, individually and combined, in beneficially modulating the microbial composition of infant and toddler (12–18 months) feces using the micro-Matrix bioreactor. In addition, the impacts of GOS and 2′-FL, individually and combined, on the outgrowth of fecal bifidobacteria at (sub)species level was investigated using the baby M-SHIME^® model. For young toddlers, significant increases in the genera Bifidobacterium, Veillonella, and Streptococcus, and decreases in Enterobacteriaceae, Clostridium XIVa, and Roseburia were observed in all supplemented fermentations. In addition, GOS, and combinations of GOS and 2′-FL, increased Collinsella and decreased Salmonella, whereas 2′-FL, and combined GOS and 2′-FL, decreased Dorea. Alpha diversity increased significantly in infants with GOS and/or 2′-FL, as well as the relative abundances of the genera Veillonella and Akkermansia with 2′-FL, and Lactobacillus with GOS. Combinations of GOS and 2′-FL significantly stimulated Veillonella, Lactobacillus, Bifidobacterium, and Streptococcus. In all supplemented fermentations, Proteobacteria decreased, with the most profound decreases accomplished by the combination of GOS and 2′-FL. When zooming in on the different (sub)species of Bifidobacterium, GOS and 2’-FL were shown to be complementary in stimulating breast-fed infant-associated subspecies of Bifidobacterium longum in a dose-dependent manner: GOS stimulated Bifidobacterium longum subsp. longum, whereas 2′-FL supported outgrowth of Bifidobacterium longum subsp. infantis.

Cranberry polyphenols (PPs) are associated with various health benefits, which can be exerted by the known parent compounds and/or through related metabolites resulting from microbial metabolization. Metabolite levels and profile/composition are often subject to extensive inter-individual variability, and many aspects of the relevant bidirectional interactions of PPs with the individual gut microbiota are still elusive. Both undigested and predigested cranberry extract were tested, next to procyanidin A2 and hyperoside controls, on the luminal and mucosa-associated gut microbial communities of six healthy adult donors in vitro. The composition of the microbial communities, polyphenolic substrate metabolization patterns, and microbial metabolites, including short-chain fatty acids (SCFAs), bile acids and aromatic acids, were analyzed at different timepoints. Both predigested and undigested cranberry extracts modulated the microbiota composition in all donors, albeit with individual variations. The mucosal samples responded differently than the luminal samples, and the type of extract also affected the composition of microbiota differently. Further, inter-individual differences in the metabolization patterns and metabolite production, such as 3,4 DHPPA (3,4-dihydroxyphenylpropionic acid), 3,4 DHPP-2-ol, and 3,4-dihydroxyphenyl acetic acid, were observed. SCFA production was stimulated with predigested cranberry extract. A semipolar compound analysis further showed much broader metabolic variations, both in cranberry-related metabolites, such as 4-vinylphenol and 3,4,5-trimethoxyphenylacetic acid, and in microbial metabolites such as indole-3-lactic acid. This study increases the knowledge on how individual microbiota samples are modulated upon exposure to cranberry-related PPs and how this influences their metabolic activity.