Validation of a novel human milk oligosaccharide for use in infant formula using gastrointestinal in vitro technologies

human gastrointestinal tract, colon, gut microbiota, Infants, Formula, prebiotic, human milk oligosaccharide, in vitro, simulator of the human intestinal microbial ecosystem (SHIME), short chain fatty acids, ammonium, lactate, DGGE, qPCR, B. longum subsp. infantis. The human body harbours a microbial community, part of which lives in the gastrointestinal tract. The colon is the region with the densest bacterial community, called gut microbiota. Its development in infants may be influenced by a number of factors, like intra-uterine environment, delivery mode and/or the feeding mode. Regarding the feeding mode, human breast milk plays an important role in early gut colonization of infants. It does so by providing a variety of human milk oligosaccharides. For infants who cannot be breastfed, infant formula is required as a substitute and so, must satisfy the nutritional requirements of infants. Since modulation of gut microbiota resorting to the addition of probiotics and/or prebiotics to the diet is increasingly becoming a recurrent practice, in order to provide infants that do not receive breast-feeding with the best possible alternative formula feeding, this study aimed to test a new human milk oligosaccharide (NMO) via gastrointestinal in vitro experiments. Firstly, a pre-screening experiment was performed to gain information on the potential inter-individual differences among babies in response to NMO administration. Overall, 7 out of the 10 donors responded strongly to the NMO treatment resulting in an acidification of the medium. A bifidogenic effect was also noted, with NMO degradation being found to occur via several different response scenarios. The choice of donor 10 was substantiated based on the strong overall fermentation and corresponding acetate production, but mainly due to a strong bifidogenic effect and thus, most interestingly, a specific stimulation of B. longum subsp. infantis upon NMO administration. Afterwards, a 5 units’ baby M-SHIME® experiment was performed using faecal sample from a single donor (donor 10) as the inoculum, making this second part of the research still exploratory. Different doses of a “golden standard” (GS) and NMO were tested. Base-acid consumption, short chain fatty acids (SCFAs), lactate, ammonium concentrations and microbiota composition were analysed. For the treatment period, 3.2 g/L of GS, NMO or combinations of thereof were supplemented to the vessels resulting in increased base-acid consumption and health-related SCFAs levels. A peak in lactate was observed for the mixtures and minor decreases were also observed on proteolytic markers. With respect to changes in Bifidobacterium composition, it followed that GS stimulated B. longum, while NMO increased the abundance of B. longum subsp. infantis with a clear dose-response effect in both situations. Over time, NMO administration caused an increase of Enterobacteria levels in a doserelated way. Given the fact that Enterobacteria also contain opportunistic pathogens, dosing would be recommended. The optimal NMO dose might therefore be the dose at which there is still a strong stimulation of B. longum ssp. infantis, and health-related SCFAs, although not resulting in a major expansion of Enterobacteria, like for example 75% / 25% or 50% / 50% (GS / NMO).