DNA-based characterization of ochratoxin-A-producing and non-producing Aspergillus carbonarius strains from grapes

Using molecular methods, a total of 189 strains of black aspergilli, including Aspergillus carbonarius and uniseriate species (Aspergillus aculeatus, Aspergillus japonicus), were studied in order to characterize species responsible for ochratoxin A (OTA) contamination of grapes from Europe and Israel. Sixty-six strains were morphologically identified as belonging to the uniseriate species and 123 as A. carbonarius. None of the uniseriate species were able to produce OTA. From the A. carbonarius strains, 96.7% were OTA producers (0.1-654.3 μg/g). We characterized 53 strains of A. carbonarius from different countries by RAPD and ITS-5.8S rDNA sequencing analysis. Forty-nine strains had a similar RAPD pattern and identical ITS-5.8S rDNA sequences. They produced OTA at different levels. No correlation was observed between the obtained clusters and the OTA production level or origin. Only four strains, morphologically identified as A. carbonarius, were unable to produce OTA. These strains showed a different RAPD pattern, and the section of DNA sequenced differed from the sequence of the other 49 strains. These OTA-non-producing strains may represent a new species in the Aspergillus section Nigri.