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

## TL;DR

This study explores bacteria in breast milk from Indian mothers to find potential probiotics and antimicrobial properties that could benefit neonate health.

## Contribution

The study identifies non-Lactobacillus bacterial strains in human milk with potential probiotic properties and antimicrobial enhancement capabilities.

## Key findings

- 381 bacterial colonies were isolated, with 38 species identified, including Gemella haemolysans and Staphylococcus strains.
- Protein extracts from isolates enhanced antimicrobial potency when combined with agents like amphotericin B.
- No antimicrobial activity was observed from isolates alone, but some showed tolerance to bile salt and NaCl.

## Abstract

Background: 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.

Aim: This study is aimed at determining the probiotic properties in the human breastmilk microbiome and their potential antimicrobial activity.

Methods: 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).

Outcome: The microbiome isolated was tested for probiotic and antimicrobial properties.

Results: Three hundred and eighty-one bacterial colonies were isolated, of which 38 different species were identified. Of these, Gemella haemolysans, Micrococcus luteus and lylae, and Staphylococcus hominis and warneri 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.

Conclusion: The non-Lactobacillus 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.