Mycobiome

Did you know that friendly moulds reside in our gut? Did you know that you ingest these microbes daily with food? Think a little about blue cheese for example.

Moulds together with yeasts belonging to the fungi kingdom live in symbiosis with a given host and are also called mycobiome. A fungal cell is almost 100 times larger than a bacterial cell, thus fungi represent substantially greater biomass than bacteria. Fungi are ubiquitous in our environment and are known to participate in natural and industrial processes including the production of antibiotics, bread, cheese, and alcoholic beverages.

Of the estimated 5 million different species of fungi in the world, only around 300 cause diseases regularly in humans. This suggests that most fungi inhabiting the human gut remain poorly explored. First, fungi may be present in human-associated niches at much lower abundance than bacteria, which are plentiful throughout the enteric tract, on the skin, and in the vagina. The mycobiome, referring principally to the fungal component of microbiome, comprises less than 2% of total gut microorganisms and is an integral part of the gastrointestinal tract. There have been several reports that fungi detected in the gut are associated with food, such as Debaryomyces coming from high salt fermented foods, Penicillium from blue cheese and Saccharomyces attributed to the consumption of yeast contained in raw fermented foods.

In fact, it has been shown that the level of Saccharomyces in the human gut is reduced to undetectable levels upon consuming a Saccharomyces-free diet. In addition, one of the most frequently reported human-associated fungal species belongs to the genus Candida. A controversial role of Candida in the human gut is reported, but it should be pointed out that not all the members of the Candida genus can be considered “bad guys”. Candida abundance, which has been found to be strongly associated with the ingestion of carbohydrates, has been identified in the intestine of healthy individuals together with the Penicillium genus and has been shown to exhibit anti-inflammatory and insulin-sensitizing activities. Research shows that fungal diversity is lower than bacterial diversity in the gut, but it is not clear whether certain fungi are resident or only transient as part of the dietary intake.