New Hydrolase from <i>Aeromicrobium</i> sp. HA for the Biodegradation of Zearalenone: Identification, Mechanism, and Application

Zearalenone (ZEN) is an estrogenic mycotoxin most frequently found in cereals that can cause reproductive disorders in livestock and pose a severe threat to animal husbandry. In this study, we isolated a ZEN-degrading Aeromicrobium strain from soil and found that ZenH, a hydrolase, is responsible for the hydrolysis of ZEN through comparative proteomics and biochemical studies. ZenH exhibited the highest similarity with lactone hydrolase ZHD607 from Phialophora americana at 21.52%. ZenH displayed maximal enzymatic activity at pH 7.0 and 55 °C with a Michaelis constant of 12.64 μM. The catalytic triad of ZenH was identified as S117-D142-H292 by molecular docking and site-directed mutagenesis. ZenH catalyzed the hydrolysis of ZEN to a novel metabolite, (S,E)-4-hydroxy-2-(10-hydroxy-6-oxoundec-1-en-1-yl)-7-oxabicyclo[4.2.0]octa-1,3,5-trien-8-one, which exhibited significantly lower estrogenic toxicity than ZEN. This study illustrates a novel ZEN-degrading enzyme and reveals a new degradation product. Furthermore, the enzyme showed good potential for detoxifying ZEN during food processing