Food contaminated with fungi can be a nuisance at best and life-threatening at worst. But new research shows that removing just one protein can leave some fungal toxins high and dry, and that’s potentially good news for food safety.
Some toxic fungi produce toxic chemicals called mycotoxins that not only spoil food such as grains but can also make us sick. Aflatoxins, one of the most dangerous types of mycotoxins, can cause liver cancer and other health problems in humans.
“It’s a silent enemy,” says Zgür Bayram, a fungal researcher at Maynooth University in Ireland, that most people don’t notice when foods like corn or wheat go bad.
For years, researchers have known that some fungi produce these toxins, but they don’t know all the details. Now, Bayram and his group of colleagues have identified the proteins responsible for converting mycotoxin production. A very kind of fungus Aspergillus nidulans even removing one of the proteins prevents toxins from forming, researchers report on Sept. 23. Nucleic Acid Research.
“There is a long string of genes involved in the production of proteins that result in the effects of various mycotoxins,” says Felicia Wu, a food safety expert at Michigan State University in East Lansing, who was not an expert in research.
The newly identified proteins act like a key in starting a car, says Bayram. The researchers wanted to figure out how to remove the key and prevent the signal from passing through it involuntarily, indicating that no toxins would be produced in the first place.
Bayram and the team identified the server A. nestingshowing that four servants must come together to make a key. The researchers genetically engineered the fungus to delete each protein in turn. When any one of the four proteins is missing, the key to mycotoxin ignition does not start, the team found.
In another study published yet, failing the same group of proteins in a fungus A. yellowwhich can make aflatoxin, prevents toxins from being made, says Bayram. “So this is a great success that we see, at least in two functions, the same” [protein] complex does the same job. “
The new work “builds on the body of research that has been done over decades” to prevent fungal contamination of food, Wu says. A wide range of methods have already been used to control such contamination. Suppose that not everyone A. yellow strains produce aflatoxins, one method to prevent contamination is to spray nontoxic strains on fields of corn and peanuts, Wu explains. Those fungi multiply and help prevent other toxic substances from taking hold.
This research is one of several ways that researchers using genetic engineering are trying to fight these toxins in food (SN: 3/10/17). One future application of the new research in general may be to implicate a toxin-making fungus and then perhaps use it in crops and elsewhere. “We can generally prevent aflatoxin contamination of food, for example, in the field, even in warehouses, where a lot of contamination occurs,” Bayram says.
Fungi and fungus-like organisms that form in water are estimated to destroy a third of edible food every year. If that contamination could be prevented, Bayram estimates that the food saved would be enough to feed 800 million people in 2022.
The new research is a good start, Wu says, but it will still be “a challenge to understand how this can be implemented for agricultural purposes.” It’s unclear how scalable the technique is, he says, and US regulatory agencies to approve the use of a genetically modified fungus on key edible crops may be difficult.
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