Transformation of Ochratoxin A by Microorganisms Isolated from Tempranillo Grapes in Wine Systems

Mycotoxins are toxic metabolites produced by different genera of fungi. Fungi belonging to species of the genera Aspergillus and Penicillium are the main source of Ochratoxin A (OTA) in wine. The reduction of OTA in must and wine has been studied using physical, chemical, and biological technologies. In this paper, we report on the capacity of different cultures isolated from Tempranillo winegrapes contaminated with fungus to degrade OTA in tryptic soy broth (TSB) medium at pH 3.5 and 6.5. The interaction between OTA and four isolates during alcoholic fermentation of red wine was studied. This study showed that microorganism isolates reduced the content of OTA in TSB medium and during wine experiment system. The microorganism that presented the greatest reduction of OTA mean in TSB medium at both pH-values corresponded to the bacteria Lactobacillus rhamnosus (55%). During the fermentation of the wine, the yeast Metschnikowia pulcherrima evidenced the best reduction of OTA (34%). OTA degradation products were identified by LC-MS/MS, in particular, α-OTA (m/z=257) and the sodium adduct of the α-OTA with the loss of coumarin group (m/z=170). The presence of OTA in must and wines is a problem in food safety. The use of lactic acid bacteria and yeasts during the winemaking process is an interesting practical application.