A novel rapid screening method for identifying aflatoxin B₁-degrading Agaricales

Food safety relies on a constant, invisible battle against natural toxins. Among the most dangerous are aflatoxins, poisonous substances produced by certain molds that can contaminate crops like corn, nuts, and grains. These toxins are notoriously difficult to remove because they do not break down easily with heat or standard cooking methods. Once they enter the food supply, they pose a serious threat to human health, capable of causing liver damage and increasing the risk of cancer. For decades, scientists have searched for ways to neutralize these toxins without destroying the food itself. One promising avenue involves using living organisms, specifically fungi, to eat or break down the poison. While some fungi are known to produce these toxins, others might possess the ability to destroy them, acting as a natural cleaning crew for our food systems.

In a recent study, researchers from Argentina set out to find which types of mushrooms could serve as this natural defense. They focused on a large group of fungi known as Agaricales, which includes many of the edible mushrooms we eat, such as oyster and button mushrooms, as well as many wild varieties. The team wanted to test if these mushrooms could not only survive in the presence of aflatoxin but actually degrade it. To do this, they developed a new, quick way to screen dozens of mushroom strains without needing expensive equipment for every single test. They gathered fifteen different strains, including wild specimens collected from various regions of Argentina and some commercially grown varieties. The goal was to see which ones could survive and thrive while breaking down the toxin.

The researchers grew these mushroom strains on a special jelly-like food made from coconut milk. They prepared two sets of this food: one plain, and one mixed with a specific amount of aflatoxin. They placed a small piece of each mushroom onto both types of plates and let them grow for twenty days in the dark. To see what was happening, they shone a special ultraviolet light on the plates. Aflatoxin naturally glows blue under this light. If a mushroom was simply growing on the plate without affecting the toxin, the blue glow would remain bright. However, if the mushroom was breaking down the toxin, that blue glow would fade or disappear entirely. This visual change served as a rapid, low-cost signal that the mushroom was doing its work.

The results revealed a clear difference between mushrooms that could tolerate the poison and those that could actually destroy it. When the toxin was present, every single mushroom strain grew more slowly than it did on the plain food, showing that the poison was stressful for them. However, the visual test showed that ten of the fifteen strains were able to completely eliminate the blue glow, indicating they had broken down the toxin to undetectable levels. Three other strains reduced the glow significantly but did not remove it entirely, while two strains showed almost no effect on the toxin. To be absolutely certain, the researchers took samples from the plates and analyzed them with a precise machine that measures chemical concentrations. This detailed analysis confirmed the visual test: the ten strains that looked like they had cleared the toxin had indeed reduced it by more than ninety-nine percent.

Perhaps the most surprising discovery was how some of these mushrooms achieved this feat. Two specific strains, one known as Cyclocybe cylindracea and another from the Stropharia family, managed to break down the toxin completely even though they did not show any visible growth on the plate. Usually, scientists expect a mushroom to be actively growing and spreading its threads to clean up a toxin. The fact that these two strains could degrade the poison without growing suggests they were releasing enzymes into the food that worked independently of the mushroom's body. This is a crucial distinction, as it implies that the cleaning power might come from the tools the fungus makes rather than the fungus itself, opening up possibilities for using these enzymes directly in food processing.

The study also highlighted that the ability to clean up aflatoxin is not something you can predict just by looking at a mushroom's name or where it was found. Some strains from the same family behaved very differently; for instance, one type of Stropharia mushroom cleaned the toxin effectively, while a closely related one did not. This means that scientists cannot simply assume a whole group of mushrooms will work; they must test each individual strain. Furthermore, the researchers noted that while the toxin was gone, the process might leave behind other chemicals that are not yet fully understood. The study confirmed that the new screening method was highly accurate and reliable, matching the results of the expensive machine tests almost perfectly.

This work provides a practical and affordable way to find new biological tools for food safety. By identifying specific mushroom strains that can neutralize aflatoxin, even without growing visibly, the researchers have opened a path toward more sustainable ways to protect our food supply. The method they developed allows for the rapid testing of many different fungi, making it easier to find the best candidates for future use. While more research is needed to understand exactly how these mushrooms break down the poison and to ensure the byproducts are safe, the findings confirm that the world of mushrooms holds significant, yet underused, potential for keeping our food free from dangerous toxins.