Characterising the Human Milk Microbiota of Indian Mothers: Prospects for Probiotic Discoveries and Antimicrobial Peptides

<b>Background:</b> The human milk microbiome is vital in the formation of the newborn microbiome and affects various health outcomes. Probiotics prevent severe necrotizing enterocolitis in neonates, but uncertainty about their safety is the obstacle to their use. Probiotic organisms and antimicrobial peptides derived from probiotic strains in human milk can offer safer options. <b>Aim:</b> This study is aimed at determining the probiotic properties in the human breastmilk microbiome and their potential antimicrobial activity. <b>Methods:</b> Study Design: We conducted a prospective longitudinal study. Participants: The study included 30 mothers, equally divided among gestational ages of < 32 weeks, 32-36 6/7 weeks, and above 37 weeks at the time of delivery. Milk samples were collected and analyzed at three different time points, that is, colostrum, transition milk (7-9 days), and mature milk (after 14 days). <b>Outcome:</b> The microbiome isolated was tested for probiotic and antimicrobial properties. <b>Results:</b> Three hundred and eighty-one bacterial colonies were isolated, of which 38 different species were identified. Of these, <i>Gemella haemolysans</i>, <i>Micrococcus luteus</i> and <i>lylae</i>, and <i>Staphylococcus hominis</i> and <i>warneri</i> were selected. Few showed bile salt, phenol, and NaCl tolerance, but none showed tolerance to pH. Antimicrobial activity was not seen when isolates or protein extracts were tested against the pathogen. Enhancement in the zone of clearance was seen when a combination of protein and antimicrobial agents was tested compared to antimicrobial alone. The zone of clearance was seen even at one-tenth of the standard concentration of amphotericin B when combined with protein extract. <b>Conclusion:</b> The non-<i>Lactobacillus</i> strains tested showed few probiotic properties. Though the isolates did not exhibit antimicrobial properties, the protein extracted from them enhanced the potency of antimicrobial agents.