Epimerization of Deoxynivalenol by the Strain A6-243 Assisted by Pyrroloquinoline Quinone.

Deoxynivalenol (DON) is a secondary metabolite produced by several species that is hazardous to humans and animals after entering food chains. In this study, by adding cofactors, the strain A6-243 is identified as the DON-transforming bacteria from a bacterial consortium with the ability to biotransform DON of sp. B6-24 and strain A6-243, and its effect on the biotransformation process of DON is studied. The strain A6-243 completely biotransformed 100 μg/mL of DON with the assistance of the exogenous addition of PQQ (pyrroloquinoline quinone) within 48 h and produced non-toxic 3-epi-DON (3-epi-deoxynivalenol), while sp. B6-24 was not able to biotransform DON, but it had the ability to generate PQQ. Moreover, the strain A6-243 not only degraded DON, but also exhibited the ability to degrade 3-keto-DON (3-keto-deoxynivalenol) with the same product 3-epi-DON, indicating that DON epimerization by the strain A6-243 is a two-step enzymatic reaction. The most suitable conditions for the biodegradation process of the strain A6-243 were a temperature of 16-37 °C and pH 7.0-10, with 15-30 μM PQQ. In addition, the strain A6-243 was found to completely remove DON (6.7 μg/g) from DON-contaminated wheat. The results presented a reference for screening microorganisms with the ability of biotransform DON and laid a foundation for the development of enzymes for the detoxification of mycotoxins in grain and its products.