Enzymatic decontamination
of Deoxynivalenol

Deoxynivalenol (DON), a mycotoxin produced by the fungus Fusarium graminearum, frequently contaminates crops, negatively impacting plant growth and crop yields.

Its presence in food and feed poses a severe threat to human and animal health¹.

DON’s toxicity is related to the hydroxyl group at the C-3 atom, which can exist in two configurations:

• ⇰ S-configuration (DON)
• ⇰ R-configuration (3-epi-DON)

Studies have shown that 3-epi-DON is at least 50 times less toxic than DON².

The conversion of DON into 3-epi-DON, which involves the formation of 3-keto-DON, is catalyzed by two classes of enzymes³:

• ⇰ PQQ-dependent dehydrogenases (DHs)
• ⇰ NADPH-dependent aldo-keto reductases (AKRs)

The aim of this study was to identify and develop two robust and efficient biocatalysts with the required industrial characteristics to deactivate DON in animal feed.

The study involved a three-step procedure:

• 1. Discovery of novel PQQ-dependent DHs and NADPH-dependent AKRs.
• 2. Cloning, expression, and purification of the newly identified DHs and AKRs.
• 3. Enzymatic characterization, reaction optimization, and engineering.

As a result of this study, it was concluded that:

• ⇰DON epimerization can be a solution for food and feed decontamination. However, reaction conditions need to be optimized.
• ⇰ This procedure allowed for the identification of 13 novel sequences (DHs and AKRs).
• ⇰ Analytical separation of epimers (DON and 3-epi-DON) can be challenging.

Considering these results, in the future, it will be important to determine if:

• ⇰ The identified DHs and AKRs enzymes operate optimally under the required industrial conditions.
• ⇰ It is possible to improve stability with rational or semi-rational engineering.

Authors