Analysis of the human breast milk microbiome and bacterial extracellular vesicles in healthy mothers

Abstract

The microbiota of human breast milk (HBM) contribute to infant gut colonization; however, whether bacterial extracellular vesicles (EVs) are present in HBM or might contribute to this process remains unknown. In this study, we characterized the HBM microbiota of healthy Korean mothers and measured the key bacteria likely affecting infant gut colonization by analyzing both the microbiota and bacterial EVs. A total of 22 HBM samples were collected from lactating mothers. The DNA of bacteria and bacteria-derived EVs was extracted from each sample. In alpha-diversity analyses, bacterial samples showed higher richness and evenness than bacterial EV samples, and beta-diversity analyses showed significant differences between bacteria and bacterial EVs within identical individual samples. Firmicutes accounted for the largest proportion among the phyla, followed by Proteobacteria, Bacteroidetes, and Actinobacteria, in both bacteria and bacterial EV samples. At the genus level, Streptococcus (25.1%) and Staphylococcus (10.7%) were predominant in bacterial samples, whereas Bacteroides (9.1%), Acinetobacter (6.9%), and Lactobacillaceae(f) (5.5%) were prevalent in bacterial EV samples. Several genera, including Bifidobacterium, were significantly positively correlated between the two samples. This study revealed the diverse bacterial communities in the HBM of healthy lactating mothers, and found that gut-associated genera accounted for a high proportion in bacterial EV samples. Our findings suggest the existence of key bacteria with metabolic activity that are independent of the major bacterial populations that inhabit HBM, and the possibility that EVs derived from these bacteria are involved in the vertical transfer of gut microbiota.

Microbiota and Metabolomic Patterns in the Breast Milk of Subjects with Celiac Disease on a Gluten-Free Diet

“…While a previous study which utilized 16S sequencing did not identify differences in the breast milk microbiota of subjects with CD compared with healthy controls [ 27 ], we identified statistically significant differences in eight bacterial species and two viral species between the two groups. The eight bacteria isolated in our study have previously been isolated from the breast milk of healthy subjects [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 ]. We did not identify breast milk literature for these bacteria in CD or other treated or untreated diseases; however, we did identify literature related to the intestinal microbiota for some of these bacteria.…”

Role of microbial dysbiosis in the pathogenesis of esophageal mucosal disease: A paradigm shift from acid to bacteria?

“…While more specific investigation is needed to evaluate the specific effects on the EM, it is likely that similarities exist in the progression due to the same factors. Human breast milk is predominantly composed of the microbes Corynebacterium, Ralstonia, Staphylococcus, Streptococcus, Serratia, Pseudomonas, Propionibacterium, Sphingomonas, and Bradyrhizobiaceae in addition to milk oligosaccharides[ 37 - 39 ].…”

More than Nutrition: Therapeutic Potential of Breast Milk-Derived Exosomes in Cancer

“…In recent years, studies on HBM components, such as human milk oligosaccharides (HMOs) and fatty acids, have been actively conducted. The HBM components that have not been well appreciated in the past, such as the microbiome, extracellular vesicles (EVs) or exosomes, and microRNAs (miRNAs), are being examined, assisted by the development of various testing techniques [11][12][13]. Some of these components consistently show no considerable differences between regions and races, such as protein components and with regard to the energy content.…”

“…Some of these components consistently show no considerable differences between regions and races, such as protein components and with regard to the energy content. However, there are differences according to the diet or weight of the breastfeeding mother in components such as vitamin A, vitamin D, water-soluble vitamins, and the composition of fatty acids, and also in other components according to the underlying condition of the breastfeeding mother [3,11,12]. In addition, the maturation, colonization, and immunity acquisition of immature intestinal mucosa are obtained through breastfeeding, and the incidence of various diseases is lower in breastfed infants than that in formula-fed infants.…”