Accidental discovery could be a mycotoxin game-changer

An enzyme that makes some mycotoxins less deadly has been discovered by a team of Agriculture and Agri-Food Canada (AAFC) scientists at the London Research and Development Centre in London, Ont.

Why it matters: Mycotoxin contamination in crops can have a huge economic impact for farmers and biofuel producers, and ingestion by humans or livestock can have serious health consequences, including death.

“I guess you could say the discovery was an accident,” Dr. Mark Sumarah, a mycotoxin and fungal expert at the London Research and Development Centre told Farmtario. 

Sumarah and his colleague Dr. Justin Renaud were originally seeking to learn more about a mycotoxin known as orchotoxin A and the potential risk of it to contaminate Canadian grapes, and consequently wine. Sumarah says orchotoxin A is a significant mycotoxin globally, but there was little data on its effect in Canada. 

Mycotoxins are toxic metabolites produced by fungi that colonize crop species which helps them to survive on plants, but when ingested they can put the health of humans and livestock at risk. 

Several years ago, the researchers were looking at the fungus Aspergillus to search for orchotoxin A, and found that Aspergillus produced not only orchotoxin A, but another type of mycotoxin known as fumonisin. Sumarah says this wasn’t unexpected, but what was a surprise is that the fungus produced strains of fumonisin that no one had seen before.

What was interesting about these compounds, says Sumarah, is that although every previously known fumonisin contains a nitrogen molecule, these new ones did not. 

“This made us very curious,” say Sumarah, and he and Renaud did further work to determine that nitrogen is the single-most important factor in the toxicity of fumonisins. 

Sumarah says “we thought that was the end of the story” but when a new researcher who specializes in enzymes, Dr. Chris Garnham, started working at AAFC in London, the team decided to delve deeper into the mechanism behind the production of the fumonisins that lacked nitrogen. 

“We figured it had to be an enzyme,” he says. 

The team then successfully isolated the enzyme responsible for converting some fumonisins into types that lack nitrogen, and began collaborating with Lallemand Inc. through a Canadian Agricultural Partnership project to commercially develop the enzyme for the detoxification of fumonisins. 

Lallemand is a privately held company based in Quebec that produces yeast, bacteria and specialty ingredients for numerous industries including baked goods, animal feeds, and biofuels, with the latter being the main target of the enzyme for the company. 

Like Deoxynivalenol (DON) or aflatoxin, fumonisins can contaminate crops such as corn and wheat and cause illness or production challenges for livestock, and become concentrated in distillers grains from biofuel production. Sumarah says that fumonisins are a worldwide problem and he has colleagues in areas where corn is a staple in the diet, such as South Africa and Latin America, who are concerned about fumonisins related to human health. Fumonisins have been linked to esophageal cancers and there is suspicion they are linked to neural tube birth defects and other cancers. 

Although DON is the biggest concern in Ontario corn, fumonisins are a significant problem in the southern U.S., and Sumarah says it is detected here. “Fumonisins would fall more in the middle [between DON and aflatoxin], but they are there. It’s something that needs to be monitored for.

“Although fumonisins are currently not a big problem in Canada, they are very likely to be a threat to Canadian crops as the climate warms up.”

The enzyme is now patent pending and shows great promise to be used as a tool to remediate fumonisin-contaminated food and feed, helping not only producers and animals but the biofuel industry, says Garnham. 

Although commercialization of the enzyme is several years away, the research trio are interested in finding an enzyme that will tackle DON.