title: Assessment of bacterial diversity in breast milk using culture-dependent and culture-independent approaches.
abstract: Initial neonatal gut colonisation is a crucial stage for developing a healthy physiology, beneficially influenced by breast-feeding. Breast milk has been shown not only to provide nutrients and bioactive/immunological compounds, but also commensal bacteria, including gut-associated anaerobic Bifidobacterium spp. The aim of the present study was to investigate bacterial diversity in breast milk, with emphasis on identifying gut-associated obligate anaerobes. Breast milk collected from seven mothers at three sampling points (days 3-6, 9-14 and 25-30 postpartum) was analysed by combined culture-dependent and state-of-the-art, culture-independent methods (Sanger sequencing and 454-pyrosequencing). In addition to the predominance of facultative anaerobes such as Staphylococcus, Streptococcus and Propionibacterium (>90% of isolated strains and 23·7% relative abundance using pyrosequencing), significant populations of obligate anaerobes, including Bifidobacterium and Veillonella, were detected using pyrosequencing and confirmed by the isolation of viable strains (3·4% of isolates and 1·4% relative abundance). Pyrosequencing also revealed the presence of DNA of multiple major gut-associated obligate anaerobes (6·2% relative abundance) such as Bacteroides and, for the first time, several members of the Clostridia, including butyrate producers, such as Faecalibacterium and Roseburia, which are important for colonic health. The present study suggests that breast milk may be a major source of bacterial diversity to the neonatal gut, including gut-associated obligate anaerobes, and may thus significantly influence gut colonisation and maturation of the immune system.
authors.affiliation: Laboratory of Food Biotechnology, Institute of Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 7, 8092 Zurich, Switzerland.
authors.forename: Ted
authors.initials: T
authors.lastname: Jost
authors.forename: Christophe
authors.initials: C
authors.lastname: Lacroix
authors.forename: Christian
authors.initials: C
authors.lastname: Braegger
authors.forename: Christophe
authors.initials: C
authors.lastname: Chassard
mesh_terms: D001419:Bacteria / Q000235:genetics; D001421:Bacteria, Anaerobic / Q000235:genetics; D046508:Culture Techniques; D004269:DNA, Bacterial / Q000032:analysis; D005260:Female; D041981:Gastrointestinal Tract / Q000382:microbiology*; D006801:Humans; D007107:Immune System / Q000254:growth & development / Q000382:microbiology; D007231:Infant, Newborn; D007774:Lactation; D054892:Metagenome / Q000235:genetics; D008895:Milk, Human / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial