Human milk oligosaccharides and infant gut microbiome in Mongolian mother-infant dyads

Human milk oligosaccharides (HMO) play crucial roles in establishing a healthy gut microbiota in breastfed infants. Many studies have been conducted using samples collected in different areas with varying lifestyles to examine the relationships between milk HMO, infant gut microbiota, and microbial HMO consumption in feces. The present study analyzed the tripartite relationship using samples obtained from Mongolian mothers and infants living in herder and urban environments, a population underrepresented in previous research. Breast milk and infant feces were cross-sectionally collected from 74 mothers and 57 infants, respectively, with 57 samples obtained from mother-infant dyads. Permutational multivariate ANOVA (PERMANOVA) using maternal metadata revealed significant effects of secretor status and lactation period on milk HMO profiles, while lifestyle differences may have exerted a slight influence during early lactation. Comparison of the milk HMO profiles of Mongolian mothers with those of mothers from other countries revealed compositional similarities among Asian populations. Of the 37 Mongolian infants receiving mature milk, 36 infants had gut microbiotas rich in bifidobacteria with relative abundances ranging from 43% to 98%. In contrast, 20 neonates who received immature milk had microbiotas characteristic of an underdeveloped transitional stage. The PERMANOVA using infant metadata revealed an association of gut microbiota profiles with delivery mode among infants receiving mature milk. No association was detected with the mother's secretor status and lifestyle differences. Further analysis suggested that the bifidobacteria-dominant gut microbiota of Mongolian infants is established by HMO consumption and cross-feeding mediated by fucosyllactose transporters or Bifidobacterium bifidum.