Aspergillus niger Ochratoxinase Is a Highly Specific, Metal-Dependent Amidohydrolase Suitable for OTA Biodetoxification in Food and Feed.

Microbial enzymes can be used as processing aids or additives in food and feed industries. Enzymatic detoxification of ochratoxin A (OTA) is a promising method to reduce OTA content. Here, we characterize the full-length enzyme ochratoxinase ( An OTA), an amidohydrolase from Aspergillus niger . An OTA hydrolyzes OTA and ochratoxin B (OTB) mycotoxins efficiently and also other substrates containing phenylalanine, alanine, or leucine residues at their C-terminal position, revealing a narrow specificity profile. An OTA lacks endopeptidase or aminoacylase activities. The structural basis of the molecular recognition by An OTA of OTA, OTB, and a wide array of model substrates has been investigated by molecular docking simulation. An OTA shows maximal hydrolytic activity at neutral pH and high temperature (65 °C) and retained high activity after prolonged incubation at 45 °C. The reduction of OTA levels in food products by An OTA has been investigated using several commercial plant-based beverages. The results showed complete degradation of OTA with no detectable modification of beverage proteins. Therefore, the addition of An OTA seems to be a useful procedure to eliminate OTA in plant-based beverages. Moreover, computational predictions of in vivo characteristics indicated that An OTA is neither an allergenic nor antigenic protein. All characteristics found for An OTA supported the suitability of its use for OTA detoxification in food and feed.