The Transient Human Mycobiome

I read an abstract[i] a couple of weeks ago…and then reread it over and over again, thinking I must be misunderstanding it.  I then put it away for a bit, and pulled it out again today to see if it still said the same thing.

It does.

So what has me so astounded?  The article[ii], in the journal of the American Society for Microbiology, describes research on the mycobiome of humans.  Specifically:  since many of the fungi found colonizing the gut are also found in food and in the mouth, the researchers wanted to separate out which ones would have a sustained influence on human health – that is, find the “true colonizers,” not the ones just passing through from our mouths or our food.

The two most prevalent species were Saccharomyces cerevisiae and Candida albicans.  The former though became undetectable when the yeast was removed from the diet, and Candida became nearly undetectable simply by more frequent teeth-brushing.  They concluded, “… that fungi do not routinely colonize the GI tracts of healthy adults.”

Unlike the other “omes,” (i.e. macrobiome, microbiome, etc.) it appears that humans do not have a native “colony” of fungi in our intestines.  In a healthy person, our mycobiome is simply a transient pass-through of various species of fungi from outside sources.  In that case, the presence of a yeast colony may be diagnostic of disease.  From the paper:  “Importantly, fungal colonization of the GI tract may often be indicative of disease. As fungi can cause serious infections in immunocompromised individuals and are found at increased abundance in multiple disorders of the GI tract [like IBD, as I have written about before, like here, for example], understanding normal fungal colonization is essential for proper treatment and prevention of fungal pathogenesis.”

Who knew?!

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[i] https://www.ncbi.nlm.nih.gov/pubmed/29600282

[ii] Auchtung, TA,, et. al. Investigating Colonization of the Healthy Adult Gastrointestinal Tract by Fung. mSphere. 2018 Mar 28;3(2).