RESUMO
BACKGROUND: The composition of the human milk microbiome is highly variable and multifactorial. Milk microbiota from various countries show striking differences. There is a paucity of data from healthy lactating Indian mothers. RESEARCH AIM: To describe the milk microbiota of healthy North Indian women, using a culture-independent, targeted metagenomic approach. METHODS: We recruited exclusively breastfeeding mothers (N = 22) who had vaginally delivered full-term singleton infants in a tertiary care hospital less than 1 week previously and had not recently consumed systemic antibiotics. Milk samples (5 ml) were collected aseptically, and microbial deoxyribonucleic acid was extracted. Microbial composition and diversity were determined using a 454-pyrosequencing platform. Core genera were identified, and their relative abundances ranked. Heatmaps showing the variation of the ranked abundances and Shannon index were obtained using R. RESULTS: Participants (all exclusively vegetarian) had a mean (SD) age of 27.2 (3.4) years, postnatal age of 3.9 (1.6) days and gestation 38 (1.2) weeks. The dominant phylum was Proteobacterium (relative abundance 84%) and dominant genus Pseudomonas (relative abundance 61.78%). Eleven species of Pseudomonas were identified, all generally considered nonpathogenic. Based on abundance patterns of the core genera, the milk samples could be grouped: (a) dominated by Pseudomonas with low diversity; (b) less Pseudomonas and high diversity; and (c) dominated by Pseudomonas but high diversity. All neonates were healthy and gaining weight well at 1 month of age. CONCLUSIONS: Healthy, lactating, vegetarian, North Indian women who deliver at term gestation and have no recent exposure to antibiotics, have a unique milk microbiome dominated by Pseudomonas.