1/5/23, 10:25 PM
NEWS
How fungi make potent toxins that can contaminate food
MICROBES
How fungi make potent toxins that can contaminate food
Genetically engineering Aspergillus species to delete certain proteins stops mycotoxin production
Genetically engineering the fungus Aspergillus nidulans (shown in this color-enhanced scanning electron micrograph) to delete
certain proteins prevents the production of compounds called mycotoxins.
EYE OF SCIENCE/SCIENCE SOURCE
By Deborah Balthazar
OCTOBER 20, 2022 AT 10:00 AM
Food contaminated with fungi can be an inconvenience 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 food such
as grains but can also make us sick. Aflatoxins, one of the more dangerous types of
mycotoxins, can cause liver cancer and other health problems in people.
https://www.sciencenews.org/article/aspergillus-fungi-mycotoxins-aflatoxin-food-contamination
1/4
1/5/23, 10:25 PM
How fungi make potent toxins that can contaminate food
Science News headlines, in your inbox
Headlines and summaries of the latest Science News articles, delivered to your
email inbox every Thursday.
Your e-mail address
SIGN UP
“It is a silent enemy,” says fungal researcher Özgür Bayram of Maynooth University in
Ireland, because most people don’t notice when food like corn or wheat is spoiled.
For years, researchers have known that some fungi produce these toxins, but didn’t
know all the details. Now, Bayram and colleagues have identified a group of proteins
responsible for turning on the production of mycotoxins. Genetically engineering the
fungus Aspergillus nidulans to remove even just one of the proteins prevents the
toxins from being made, the researchers report in the Sept. 23 issue of Nucleic Acids
Research.
“There is a long string of genes that is involved with 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 research.
The newly identified proteins act like a key starting a car, Bayram says. The
researchers wanted to figure out how to remove the key and prevent the starting
signal from going through, meaning that no toxins would be made 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
delete each protein in turn. When any of the four proteins are missing, the key does
not start mycotoxin ignition, the team found.
https://www.sciencenews.org/article/aspergillus-fungi-mycotoxins-aflatoxin-food-contamination
2/4
1/5/23, 10:25 PM
How fungi make potent toxins that can contaminate food
In another study that has yet to be published, deactivating the same group of proteins
in the closely related fungus A. flavus, which can make aflatoxins, prevents the
production of those toxins, Bayram says. “So this is a big success because we see, at
least in two fungi, the same [protein] complex does the same job.”
The new work “is building upon a body of research that’s been done over decades” to
prevent fungal contamination of food, Wu says. A range of methods are already used
to control such contamination. For instance, because not all A. flavus strains produce
aflatoxins, one method to prevent contamination is to sprinkle nontoxic strains onto
fields of corn and peanuts, Wu explains. Those fungi multiply and can help prevent
other toxic strains from gaining a foothold.
Subscribe to Science News
Get great science journalism, from the most trusted source, delivered to
your doorstep.
SUBSCRIBE
This research is one of several ways that researchers are using genetic engineering to
try to combat these toxins in food (SN: 3/10/17). One future application of the new
research could be to genetically tweak a toxin-making fungus and then possibly use it
on crops and elsewhere. “We can basically prevent aflatoxin contamination in food,
for example, in the field, even in the warehouses, where a lot of contamination takes
place,” Bayram says.
Fungi and fungi-like organisms known as water molds are estimated to ruin a third of
the world’s food crops each year. If that contamination could be prevented, Bayram
estimates the saved food 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 try to
understand how this can be operationalized for agricultural purposes.” It’s unclear
https://www.sciencenews.org/article/aspergillus-fungi-mycotoxins-aflatoxin-food-contamination
3/4
1/5/23, 10:25 PM
How fungi make potent toxins that can contaminate food
how scalable the technique is, she says, and getting U.S. regulatory agencies to
approve the use of a genetically modified fungus on key food crops might be difficult.
CITATIONS
B. Karahoda et al. The KdmB-EcoA-RpdA-SntB chromatin complex binds regulatory genes and coordinates fungal development
with mycotoxin synthesis. Nucleic Acids Research. Vol. 50, September 23, 2022, p. 9797. doi: 10.1093/nar/gkac744.
This article was supported by readers
like you.
Our mission is to provide accurate, engaging news of science to the
public. That mission has never been more important than it is today.
As a nonprofit news organization, we cannot do it without you.
Your support enables us to keep our content free and accessible to the
next generation of scientists and engineers. Invest in quality science
journalism by donating today.
DONATE NOW
https://www.sciencenews.org/article/aspergillus-fungi-mycotoxins-aflatoxin-food-contamination
4/4