(P20-006-23) Characterization of Human Milk Microbiome Intended for Female and Male Infants in Ecuadorian Lactating Women and Its Potential Association With Free Amino Acids Metabolism

Objectives: To characterize the human milk-microbiome in colostrum, transition, and mature milk and its potential association with free amino acid (FAA) metabolism in milk intended for female and male infants at term.

Methods: This longitudinal cohort study included adult primiparous healthy mothers that had given birth to vigorous full-term babies via vaginal deliveries. Human milk samples were collected aseptically with a manual sterile pump from both breasts and processed within two hours. Bacterial DNA from HM was isolated, and 16S rRNA was amplified and sequenced on Illumina MiSeq. Bioinformatic analysis was performed using QIIME2; the metabolomic potential of 16S rRNA was analyzed with PICRUST2. Sociodemographic and clinical characteristics of participating lactating mothers and their children were obtained from their clinical records.

Results: Most women were housewives, mestizo, single, and with high school education. There were statistically significant differences in microbiota α-diversity in the three lactation periods (Shannon diversity index; Kruskal Wallis test, p< 0.05); α -diversity was also different when considering the sex of the children in colostrum. β−diversity was significantly different between Colostrum vs. Mature milk (Bray-Curtis; p< 0.05) and Transition vs. Mature milk (Bray-Curtis; p< 0.05); β−diversity was different in colostrum for females and males (Bray-Curtis; p< 0.05). α -diversity of functional profiles in HM was not statistically different during lactation. However, there were significant differences in β-diversity between colostrum and mature HM intended for females; 33 metabolic pathways differed significantly between these two periods (Welch’s t-test P < 0.005); ten were more abundant in mature milk than in colostrum, including those related with amino acid, fat, and vitamin metabolism while 23 pathways related with energy and vitamin metabolism were more abundant in colostrum. Predicted MH metabolomic functionality showed seven main metabolic pathways related to carbohydrate, fat, and L-glutamate metabolism during lactation.

Conclusions: Human milk microbiome composition and its predicted function significantly changed in adult Ecuadorian mothers during the study period and could be related to the infants’ gender.

Funding Sources: International Glutamate Technical Committee / IGTC