AUTHOR=Fernández Leónides , Pannaraj Pia S. , Rautava Samuli , Rodríguez Juan M. 

TITLE=The Microbiota of the Human Mammary Ecosystem

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=Volume 10 - 2020

YEAR=2020

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2020.586667

DOI=10.3389/fcimb.2020.586667

ISSN=2235-2988

ABSTRACT=Human milk contains a dynamic and complex site-specific microbiome which is not assembled in an aleatory way but forming organized bacterial consortia and networks. Culture-independent studies have confirmed the presence of DNA from previously cultured bacterial groups, such as staphylococci, streptococci, corynebacteria, cutibacteria, lactic acid bacteria or bifidobacterias. DNA from some gut-associated strict anaerobes which are generally regarded as non-cultivable bacteria has also been repeatedly found. Recent studies reinforce the hypothesis that at least some bacteria, including obligate anaerobes, may be vertically transferred from mother to neonate via breastfeeding. Still, the significance and contribution of the bacteria in human milk to infant gut colonization remains an open question. Clinical studies trying to elucidate the question are confounded by the profound impact of non-microbial human milk components to intestinal microecology. Additionally, some studies have revealed the presence of cells and/or DNA from viruses, archaea, fungi and protozoa in human milk. Modifications in the composition of the human milk microbiome may have biological implications for infant colonization, metabolism, immune and neuroendocrine development and for mammary health. However, little is known about the factors driving differences in the composition of the human milk microbiome. This and other open issues, such as the origin of the human milk microbiome, and our current limitations and future prospects and are addressed in this review.