Lactation-dependent vertical transmission of natural probiotics from mother to infant gut through breast milk

The transmission of certain bacteria from the mother's gut to the infant's gut via breast milk (BM) is critical for offspring's immune system development. Dysbiosis of the BM microbiota can be caused by a variety of reasons, which can be influenced by probiotics delivered via the enteromammary route. The goal of this study was to investigate the bacterium that can be transmitted from mother to infant's intestine during various lactation periods in 19 mother-child dyads. Bacterial transmission is most common during the colostrum phase when bacteria with certain amplicon sequence variants (ASVs) enter the newborn intestine and inhabit it permanently. We have established that anaerobic gut-associated bacteria, such as Faecalibacterium, Blautia and Lachnoclostridium, transfer from the mother to the infant's gut with lactation dependence using the idea of weighted transfer ratios. Streptococcus salivarius, Bifidobacterium longum, and Lactobacillus gasseri were transferred from the maternal gut to the BM, as well as from the BM to the newborn gut, dependent on different ASVs. These findings suggest that isolating key microorganisms from breast milk could be utilized to modify the microbiota of BM or newborns by giving the mother a probiotic or adding it to artificial milk to promote neonatal health.