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Microbiota and food contaminants: a mycotoxin amplifies the genotoxic action of a gut bacterium (2017-04-10)

Researchers at the French National Institute for Agricultural Research (Inra) and their partners have been studying the interactions between the bacterial microbiota and a common food contaminant: the mycotoxin deoxynivalenol (DON).
They found that the presence of DON enhances the genotoxic effects of certain bacteria.

Fusarium gramineraum, a fungus that produces deoxynivalenol © INRA, Sylviane BAILLY

More specifically, it increases the damage caused to the DNA of intestinal cells, contributing to the appearance of cancerous cells.

This work raises important questions regarding how potential synergies between food contaminants and the intestinal microbiota could contribute to colorectal cancer development.

The human intestinal microbiota contains around 100,000 billion bacteria belonging to very diverse species.
A common intestinal resident is Escherichia coli, and E. coli strains form different phylogenetic groups.

E. coli group B2 bacteria produce a genotoxic substance, i.e. a product that damages the DNA of intestinal cells, known as colibactin.

An increase has been noted in the number of group B2 bacteria in the gut microbiota of populations from industrialised countries.

Mycotoxins are the most common natural contaminants present in human and animal food.

One of these, deoxynivalenol (DON), is produced by moulds from the Fusarium family, which mainly develop in cereals.
The human populations in Europe and North America are widely exposed to it in their food.
In France and Europe, exposure of some fractions of the population, especially children, exceeds the toxicity reference values for this toxin.

The Inra researchers and their partners conducted in vitro and in vivo animal studies to see what happened when colibactin-producing Escherichia coli and DON were simultaneously present in the gut.

In animals colonised with colibactin-producing bacteria and exposed to DON in their food, the DNA damage to intestinal cells was significantly greater, compared with animals not producing colibactin.
They thus show that the presence of the mycotoxin enhances the genotoxicity of group B2 E. coli.

These first results provide new data regarding possible synergy between food contaminants and the gut microbiota. The researchers will continue to work to elucidate the mechanism involved in this enhanced genotoxicity in the presence of DON, and studies are planned to extend the observations up to an advanced stage of colorectal carcinogenesis.

For more information
mBio - American Society for Microbiology
The Food Contaminant Deoxynivalenol Exacerbates the Genotoxicity of Gut Microbiota

INRA - Institut national de la recherche agronomique

Institut national de la santé et de la recherche médicale