| Summary: | During the 2001 wine vintage, grapes were sampled at harvest time in eleven vineyards located in four Portuguese wine regions (from north to south: Vinhos Verdes, Douro, Ribatejo and Alentejo) for filamentous fungi isolation and identification, and for ochratoxin A (OTA) analysis. In all studied vineyards, fungi isolates belonging to Penicillium and Aspergillus recognized as producers of OTA were tested to detect its production. Also, several strains were assessed for their ability to degrade OTA in other compounds. The Penicillium isolates were not OTA producers, although some were able to degrade OTA. Many of the Aspergillus strains belong to the black Aspergillus section, mainly: A. niger aggregate and A. carbonarius. Not all the strains from the above-mentioned Aspergillus were able to produce OTA, but most of them were able to degrade OTA. It was found that just 13 out of 207 A. niger aggregate and 32 out of 33 A. carbonarius were OTA producers. Furthermore, all the black Aspergillus tested were able to degrade OTA, in many cases to the less toxic ochratoxin a. It was also observed a prevalence of not OTA producer strains over the producer ones, and many of these not OTA producer strains were able to degrade OTA. The presence of OTA in grapes from all sampled vineyards was determined. However, it was not possible to correlate the presence of OTA in grapes with the presence of OTA producer strains in the same grapes. The possibility that the presence of OTA in grapes is due to in vivo interactions between the ability to produce and to degrade the mycotoxin by fungi is suggested.
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