Distinct fiber effect in ex vivo Kenyan infant gut microbiota
Iron fortification to prevent anemia in infants from developing countries increases colonic iron levels, favouring the growth of enteropathogens. The use of prebiotics was suggested as an effective strategy to reduce these detrimental effects. Using the recently developed African infant PolyFermS continuous gut model (n= 4), we compared the effect of three fiber mixtures, including the established prebiotics short-chain galacto- with long-chain fructo-oligosaccharides (scGOS/lcFOS) and native inulin, and the emerging prebiotic acacia gum during iron supplementation on the Kenyan infant gut microbiota.  Ex vivo iron supplementation did not lead to a major shift in microbiota composition or metabolite production but promoted Clostridioides difficile in one microbiota. The prebiotic effect of scGOS/lcFOS and inulin was confirmed during iron supplementation in all investigated Kenyan infant gut microbiota, leading to more growth of bifidobacteria, increased production of acetate, propionate and butyrate, and a significant shift in microbiota composition compared to non-supplemented microbiota. The growth of the pathogens C. difficile and Clostridium perfringens was also inhibited upon addition of the prebiotic fibers compared to the non-supplemented microbiota. Acacia gum had no effect on any of the microbiota.  In conclusion, scGOS/lcFOS and inulin, but not acacia gum, showed a donor-independent strong prebiotic potential in Kenyan infant gut microbiota by promoting bifidobacteria growth and inhibiting enteropathogens through enhanced SCFA production. Therefore, this study demonstrates the relevance of comparing fibers in the target population in vitro prior to in vivo clinical studies, and is a first step towards more precise microbiome-targeted nutritional solutions.