Fungal-contaminated food can be inconvenient 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 fungi produce toxic chemicals called mycotoxins that not only spoil foods, 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 people.
“It’s a silent enemy,” says fungal researcher Özgür Bayram of Maynooth University in Ireland, because most people don’t realize when foods like corn or wheat spoil.
For years, researchers have known that some fungi produce these toxins, but they didn’t know all the details. Now, Bayram and his colleagues have identified a group of proteins responsible for activating the production of mycotoxins. Genetic engineering of the fungus Aspergillus nidulans removing even one of the proteins prevents the toxins from being produced, the researchers report in the September 23 issue of Nucleic acid research.
“There is a long chain of genes that are involved in the production of proteins that, in a cascading effect, will result in the production of different mycotoxins,” says Felicia Wu, a food safety expert at Michigan State University in East Lansing, who was not involved in the investigation.
The newly identified proteins act like a key that starts a car, says Bayram. The researchers wanted to figure out how to remove the key and prevent the start signal from being emitted, meaning no toxins would be produced in the first place.
Bayram and his team identified the proteins in A. nidulans, revealing that four proteins come together to make the key. The researchers genetically engineered the fungus to remove each protein in turn. When any of the four proteins are missing, the key doesn’t initiate mycotoxin ignition, the team found.
In another study that has not yet been published, the inactivation of the same group of proteins in the closely related fungus A. flavus, which can produce aflatoxins, prevents the production of those toxins, says Bayram. “So this is a huge success because we see, in at least two fungi, the same [protein] complex does the same job.”
The new work “builds on a body of research that has been done for decades” to prevent fungal contamination of food, says Wu. A number of methods are already used to control such contamination. For example, because not all A. flavus The strains produce aflatoxins, one method to prevent contamination is to spray non-toxic strains in corn and peanut fields, Wu explains. Those fungi multiply and can help prevent other toxic strains from taking hold.
This research is one of several ways researchers are using genetic engineering to try to combat these toxins in food (Serial number: 03/10/17). One future application of the new research could be to genetically modify a toxin-producing fungus and then possibly use it in crops and elsewhere. “Basically, we can prevent aflatoxin contamination in food, for example, in the field, even in warehouses, where a lot of contamination occurs,” says Bayram.
Fungi and fungus-like organisms known as water molds are thought to ruin a third of the world’s food crops each year. If that contamination could be prevented, Bayram estimates that the food saved would be enough to feed 800 million people by 2022.
The new research is a good start, says Wu, but it will remain a “challenge in trying to understand how this can be put into practice for agricultural purposes.” It’s not clear how scalable the technique is, she says, and getting US regulatory agencies to approve the use of a genetically modified fungus on key food crops could be difficult.