The mechanisms involved in ochratoxin A elimination by Yarrowia lipolytica Y-2

Biological control of mycotoxin in cereals, fruits and vegetables have emerged as a promising method. In a previous study, Yarrowia lipolytica Y-2 isolated by our research team showed biocontrol effect on the post-harvest decay of grapes and ochratoxin A (OTA) elimination in polytoma medium. The aim of this study was to elucidate the possible mechanisms of OTA elimination by Y. lipolytica Y-2. The results indicated that OTA elimination by Y. lipolytica Y-2 was attributed to the degradation action of intracellular enzymes but not extracellular enzymes. A degradation product was identified as ochratoxin alpha (OT alpha) by liquid chromatography-tandem mass spectrometry. The intracellular enzymes precipitated with 65% saturation of ammonium sulphate degrade OTA the most quickly and 97.2% OTA was degraded within 4 h. Analysis of this fraction showed that two proteins of carboxypeptidase were expressed in Y. lipolytica Y-2 but not in Y. lipolytica Polh without the ability to degrade OTA. The results of the protein identification combined with product identification indicated that OTA was degraded to OT alpha by Y. lipolytica Y-2 through the hydrolysis activity of carboxypeptidases. Additionally, many proteins of Y. lipolytica Y-2 involved in stress response and reactive O-2 species elimination also played essential role in OTA degradation.