Multiple Approaches Detect the Presence of Fungi in Human Breastmilk Samples from Healthy Mothers

Abstract

Human breastmilk contains a variety of bacteria that are transmitted to the infant and have been suggested to contribute to gut microbiota development and immune maturation. However, the characterization of fungal organisms in milk from healthy mothers is currently unknown although their presence has been reported in the infant gut and also in milk from other mammals. Breastmilk samples from healthy lactating mothers (n = 65) within 1 month after birth were analyzed. Fungal presence was assessed by different techniques, including microscopy, growth and identification of cultured isolates, fungal load estimation by qPCR, and fungal composition using 28S rRNA gene high-throughput sequencing. In addition, milk macronutrients and human somatic cells were quantified by spectrophotometry and cytometry. qPCR data showed that 89% of samples had detectable levels of fungal DNA, at an estimated median load of 3,5 × 105 cells/ml, potentially including both viable and non-viable fungi. Using different culture media, 33 strains were isolated and identified, confirming the presence of viable fungal species. Pyrosequencing results showed that the most common genera were Malassezia (44%), followed by Candida (19%) and Saccharomyces (12%). Yeast cells were observed by fluorescence microscopy. Future work should study the origin of these fungi and their potential contribution to infant health.

Mycobiome Profiles in Breast Milk from Healthy Women Depend on Mode of Delivery, Geographic Location, and Interaction with Bacteria

“…At the genus level, Malassezia predominated in all countries, followed by Davidiella. In our previous work reporting the presence of fungi in breast milk, Malassezia also represented the most abundant genus (20). Other genera found in the current study, such as Alternaria, Rhodotorula, Saccharomyces, and Candida, were also found in the previous study.…”

“…Breast milk is a continuous source of microbes that are transmitted, together with many nutrients and protective compounds, to the infant gut during a critical period when the key regulatory systems of the body are immature (17,18). Although bacteria inhabiting human breast milk have been extensively studied, the presence of fungi in the fluid had not been assessed until recently, when a diversity of fungal phylotypes in breast milk from healthy Spanish mothers was reported by our group (20). The mycobiome, the fungal fraction of the human microbiome, is present in lower abundances and has been much less explored than the bacterial fraction.…”

“…Breast milk is an important source of bacteria to the infant, and together with oligosaccharides, contributes to the settlement of the gut microbiota characteristic of the healthy breast-fed child, with a strong impact on immune surveillance within the gastrointestinal environment and thereby also other membranes of the body (17)(18)(19). A recent study suggested the presence of a diversity of fungal species in human breast milk of healthy mothers, including Malassezia, Candida, and Saccharomyces as the most common genera, by means of high-throughput sequencing, microscopy, and other culture-independent techniques (20). Moreover, viable yeasts, predominantly Candida parapsilosis and Rhodotorula mucilaginosa species, were isolated and characterized.…”

Review: Are there indigenous Saccharomyces in the digestive tract of livestock animal species? Implications for health, nutrition and productivity traits

“…This is very interesting because it may imply that human beings are exposed to Saccharomyces since very early in life. In this paper, the authors discussed that this may be due to skin contamination and also raise the intriguing possibility of an entero-mammary pathway involving an internal route (Boix-Amorós et al, 2017). Saccharomyces has also been detected in human faeces a number of times (Nash et al, 2017), being sometimes the dominant genus representing over half of total relative abundance (Huseyin et al, 2017).…”

“…Saccharomyces is an abundant (average 15% of all sequence reads) and prevalent member of the milk mycobiome in healthy mothers (Boix-Amorós et al, 2017). This is very interesting because it may imply that human beings are exposed to Saccharomyces since very early in life.…”