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Serum-derived bovine immunoglobulins (SBI) exert health benefits mediated by their ability to bind microbial components, thereby preventing translocation and subsequent inflammation. While in vivo studies have shown that a fraction of SBI also reaches the colon, little is known about the impact of SBI on the dense colonic microbiota that has great potential to impact human health. This study, therefore, investigated the impact of three bovine plasma protein fractions (SBI, bovine plasma (BP) and albumin-enriched bovine plasma (ABP)) on the gut microbiota of six human adults using the novel ex vivo SIFR® technology, recently demonstrated to generate predictive findings for clinical studies. When dosed at an equivalent of 5 g/day, all protein fractions significantly increased health-related metabolites—acetate, propionate, and butyrate. Upon simulating small intestinal absorption, SBI still markedly increased acetate and propionate, demonstrating that SBI is more resistant to small intestinal digestion and absorption compared to the other protein sources. Despite noticeable interindividual differences in microbiota composition among human adults, SBI consistently stimulated a narrow spectrum of gut microbes, which largely differed from the ones that are typically involved in carbohydrate fermentation. The SBI-fermenting consortium included B. vulgatus and L. edouardi (correlating with acetate and propionate) along with Dorea longicatena, Coprococcus comes and the butyrate-producing bacterium SS3/4 (correlating with butyrate). Overall, this study revealed that protein bovine fractions can contribute to health benefits by specifically modulating the human gut microbiota. While health benefits could follow from the production of SCFA, a broader range of protein-derived metabolites could also be produced. This study also confirms that the concept of prebiotics (substrates selectively utilized by host microorganisms conferring a health benefit) could go beyond the use of ingestible carbohydrates and extend to partially indigestible proteins. [ABSTRACT FROM AUTHOR]

The human gut microbiome is currently recognized to play a vital role in human biology and development, with diet as a major modulator. Therefore, novel indigestible polysaccharides that confer a health benefit upon their fermentation by the microbiome are under investigation. Based on the recently demonstrated prebiotic potential of a carrot-derived pectin extract enriched for rhamnogalacturonan I (cRG-I), the current study aimed to assess the impact of cRG-I upon repeated administration using the M-SHIME technology (3 weeks at 3g cRG-I/d). Consistent effects across four simulated adult donors included enhanced levels of acetate (+21.1 mM), propionate (+17.6 mM), and to a lesser extent butyrate (+4.1 mM), coinciding with a marked increase of OTUs related to Bacteroides dorei and Prevotella species with versatile enzymatic potential likely allowing them to serve as primary degraders of cRG-I. These Bacteroidetes members are able to produce succinate, explaining the consistent increase of an OTU related to the succinate-converting Phascolarctobacterium faecium (+0.47 log10(cells/mL)). While the Bifidobacteriaceae family remained unaffected, a specific OTU related to Bifidobacterium longum increased significantly upon cRG-I treatment (+1.32 log10(cells/mL)). Additional monoculture experiments suggested that Bifidobacterium species are unable to ferment cRG-I structures as such and that B. longum probably feeds on arabinan and galactan side chains of cRG-I, released by aforementioned Bacteroidetes members. Overall, this study confirms the prebiotic potential of cRG-I and additionally highlights the marked consistency of the microbial changes observed across simulated subjects, suggesting the involvement of a specialized consortium in cRG-I fermentation by the human gut microbiome. [ABSTRACT FROM AUTHOR]