Next Generation Grain Tests Help Make Mycotoxin Testing Safer, Easier

“The ability to test the same sample for up to six mycotoxins represents a potentially significant cost and time savings for grain testers,” says Mary Gadola, Neogen’s product manager for natural toxin products. “Until now, testers had no choice but to prepare separate samples for each mycotoxin to be tested for—by far the largest time-consuming element of the entire testing process. The newest testing products will eliminate the need for that duplication—and associated costs.”

The two most commonly tested mycotoxins are aflatoxin, a toxin primarily produced by Aspergillus species molds, and DON, a toxin primarily produced by Fusarium species molds. As Aspergillus and Fusarium molds also create other mycotoxins, testers commonly test for other toxins created by the same species of mold.

Toxins Produced by Molds

Aflatoxin is a toxic and carcinogenic substance produced by certain strains of the molds
Aspergillus flavus and Aspergillus parasiticus. The effects in animals of ingesting excessive amounts of the toxin range from chronic health and performance problems to death. The FDA and many other global regulatory agencies have set maximum allowable levels of aflatoxin in food and feed.

Ochratoxin is commonly produced by the molds Aspergillus ochraceus and Penicillium viridicatum. Ochratoxin may be present in conjunction with aflatoxin, one of the most potent naturally occurring carcinogens. In fact, ochratoxin is a suspected carcinogen.

DON is most commonly produced by the pink mold Fusarium graminearum. DON, a member of the trichothecene family, is produced by fungi living on cereal commodities. The toxicological effects attributed to DON include: nausea (vomiting), feed refusal, gastroenteritis, diarrhea, immunosuppression, and blood disorders.

Zearalenone is also primarily produced by the mold Fusarium graminearum, which also commonly produces DON. Hence, there is evidence that if zearalenone is detected, there is a high probability that other fusarial mycotoxins may be present. Zearalenone is classified as an estrogenic mycotoxin because it frequently causes estrogenic responses in animals.

Fumonisins are a family of mycotoxins produced by different species of the mold Fusarium. These molds commonly infect corn (in fact, they are considered ubiquitous in corn) and rice. Therefore, the potential for fumonisins to be found in feed and foodstuffs is high. Fumonisins affect various animals differently and have been linked to esophageal cancer in humans. Horses are extremely sensitive to low amounts of fumonisin, which can cause leukoencephalomalcia (liquefaction of the brain).

T-2/HT-2 toxins are trichothecene mycotoxins produced by several species of Fusarium molds. As T-2 toxin is readily metabolized to HT-2 toxin, and the toxins have been shown to produce numerous adverse effects on many animals, these two mycotoxins are frequently evaluated together.

New Generation of ELISA Example

One example of the next generation of tests is a single-step lateral flow immunochromatographic assay based on a competitive immunoassay format. The sample extract is wicked through a reagent zone, which contains antibodies specific for target mycotoxin conjugated to colloidal gold particles. If the target is present, it will be captured by the particle-antibody complex.

The mycotoxin-antibody-particle complex is then wicked onto a membrane, which contains a zone of aflatoxin conjugated to a protein carrier. This zone captures any uncomplexed mycotoxin antibody, allowing the particles to concentrate and form a visible line.

As the level of target mycotoxin in a sample increases, free mycotoxin will combine with the antibody-gold particles. This allows less antibody-gold to be captured in the test zone. Therefore, as the concentration of mycotoxin in the sample increases, the test line density decreases. Algorithms programmed into the test strip readers convert these line densities into a quantitative result displayed in parts per billion or parts per million.

Topper is the market development manager at Neogen Corp., working with the milling and grain division. Reach him at [email protected].