A study that sampled breast milk from several countries
including South Africa has found that the breast milk microbiome contains
fungi. Multiple previous studies had found bacteria in breast milk. Certain
fungi and bacteria have been shown to be important probiotics for infant
health. The research is published in Applied and Environmental Microbiology, a journal of the American
Society for Microbiology. 

“Our research demonstrates the presence of yeasts and other fungi in breast
milk in healthy mothers, supporting the hypothesis that breast milk is an
important source of microorganisms to the growing infant,” said principal
investigator Maria Carmen Collado, PhD, Senior Researcher, the Institute of
Agrochemistry and Food Technology, National Research Council, Valencia,
Spain. 
 
Having established in earlier research the presence of yeasts and other fungi
in breast milk from mothers in Spain, the investigators sampled breast milk
from mothers in other geographic locations, including Finland, China, and South
Africa, to find out whether this finding held up in locations with different
weather, diets, and lifestyles from those in southern Europe. 
 
“Our data confirm the presence of fungi in breast milk across continents and
support the potential role of breast milk on the initial seeding of fungal
species to the infant gut,” the investigators wrote. “This supports the
existence of a ‘breast milk mycobiota’ under healthy conditions.”
 
The genera Malassezia and Davidiella were most prevalent
across the different countries. Those two, as well as Sistotrema and Penicillium,
were present in breast milk from each country. 
 
More than 70% of Spanish and South African samples had detectable levels of
fungal DNA, while only 45% of Chinese samples and only 35% of Finnish samples
did. Despite the similarities of the mycobiomes across the four countries, “Our
findings reinforce the potential influence of environmental factors, in
particular geographic location, on the species of yeast and fungi that make up
the breast milk mycobiome,” said Dr Collado.
 
The investigators also compared the breast milk mycobiome in mothers who had
delivered vaginally with that from mothers who had delivered via cesarean
section. Specific fungi, such as those of the genus Cryptococcus, were
more prevalent among samples from mothers delivering vaginally, but mode of
delivery made no difference in fungal diversity or richness. 
 
The investigators did not identify the sources of the breast milk mycobiome,
but Malassezia are found in around the sebaceous glands, glands that
secrete oils to lubricate hair and skin. Davidiella have been found
in the vagina. And Saccharomyces, also present in breast milk, are among
the most abundant fungi in the gut. 
 
Viable fungal cells within the breast milk suggest that breast milk could
influence development of infants’ mycobiota, the researchers wrote. “However,
little is known about the development of mycobiota in infants,” said Dr
Collado. 
 
“Currently, some yeast species are used as potential probiotics to promote
infant health,” said Dr. Collado. “The most common one is Saccharomyces
boulardii. Our study identifies more fungal species that could potentially
confer benefits for human health, and the possibility of isolating appropriate
strains from breast milk. Those potential benefits should now be studied in
detail.” 

Source: https://www.asm.org/Press-Releases/Breast-Milk-Microbiome-Contains-Yeast-and-Fungi-Do

Reference: https://aem.asm.org/content/aem/early/2019/02/25/AEM.02994-18.full.pdf?ijkey=tM78Lxo8YHwbQ&keytype=ref&siteid=asmjournals