Modification of deoxynivalenol by a fungal laccase paired with redox mediator TEMPO

Authors: SHANAKHAT, HINA - University Of Naples; McCormick, Susan; Busman, Mark; Rich, Joseph; BAKKER, MATTHEW - University Of Manitoba

Submitted to: Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/9/2022
Publication Date: 8/11/2022
Citation: Shanakhat, H., McCormick, S.P., Busman, M., Rich, J.O., Bakker, M.G. 2022. Modification of deoxynivalenol by a fungal laccase paired with redox mediator TEMPO. Toxins. 14(8). Article 548. https://doi.org/10.3390/toxins14080548.
DOI: https://doi.org/10.3390/toxins14080548

Interpretive Summary: Grain contaminated with fungal toxins called mycotoxins can cause billions of dollars in annual yield losses. The mycotoxin deoxynivalenol (DON) is produced by Fusarium graminearum, a fungus that causes Fusarium Head blight of wheat and barley and ear rot of corn. DON is harmful to the health of humans and livestock and can cause diarrhea, abdominal pain, vomiting, and skin irritation. Technologies to reduce or eliminate the toxicity of deoxynivalenol are needed to preserve the value of grain and grain byproducts after ethanol production. Therefore, we screened commercially available enzymes to identify ways of disarming the toxins. We found that a fungal laccase that in combination with a chemical mediator called TEMPO completely transformed DON and chemically characterized potential detoxification products. This work can serve as a guide for finding effective enzymatic treatment of contaminated grain.

Technical Abstract: Mycotoxins such as deoxynivalenol introduce a health risk to the food supply and are costly to manage or avoid. Technologies for reducing or eliminating the toxicity of deoxynivalenol could be useful in a variety of processes, such as in preserving the value as animal feed of byproducts of ethanol production. Using chromatography, mass spectrometry, and nuclear magnetic resonance spectroscopy, we characterized transformation products of deoxynivalenol that were formed by the combination of a fungal laccase paired with a chemical mediator. Alcohol groups at the C3 and C15 positions of deoxynivalenol were oxidized to ketones, and the chemical mediator became covalently linked to the C4 position. Conditions experienced during gas chromatography led to the dissociation of the chemical mediator, forming 3,15-diketodeoxynivalenol. Understanding the range of possible modifications to deoxynivalenol and other trichothecene is a necessary step toward effective remediation of contaminated grain.