Association of Maternal Secretor Status and Human Milk Oligosaccharides With Milk Microbiota: An Observational Pilot Study

Background and Objectives: Breast milk contains several bioactive factors including oligosaccharides (HMO) and microbes that shape the infant gut microbiota. HMO profile is determined by secretor status, however their influence on milk microbiota is still uncovered. This study is aimed to determine the impact of the FUT2 genotype on the milk microbiota during the first month of lactation and the association with HMO. Methods: Milk microbiota from 25 healthy lactating women was determined by quantitative PCR and 16S gene pyrosequencing. Secretor genotype was obtained by PCR-RFLPs and by HMO identification and quantification. Results: The most abundant bacteria were Staphylococcus and Streptococcus, followed by enterobacteriaceae-related bacteria. The predominant HMO in secretor milk samples were 2FL and LNFP I whereas non-secretor milk was characterized by LNFP II and LNDFH II. Differences in microbiota composition and quantity were found depending on secretor/non-secretor status. Lactobacillus spp, Enterococcus spp., and Streptococcus spp. were lower in non-secretor than in secretor samples. Bifidobacterium genus and species were less prevalent in non-secretor samples. Despite no differences on diversity and richness, non-secretor samples had lower Actinobacteria and higher relative abundance of Enterobacteriaceae, Lactobacillaceae and Staphylococcaceae. Conclusions: Maternal secretor status is associated with the human milk microbiota composition and is maintained during the first 4 weeks. Specific associations between milk microbiota, HMO and secretor status were observed although the potential biological impact on the neonate remains elusive. Future studies are needed to reveal the early nutrition influence on the reduction of risk of disease.European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (ERC Starting Grant, 639226).Peer reviewe