Assessment of the ochratoxin A production ability of Aspergillus tubingensis.

Aspergillus tubingensis is a black Aspergillus frequently isolated from different agricultural products, including grapes. Conflicting results have been published in recent years about its ability to produce ochratoxin A (OTA), a potent nephrotoxic and carcinogenic mycotoxin. This study re-examined six A. tubingensis strains deposited in international culture collections for OTA production. OTA could not be detected in any A. tubingensis extract using HPLC coupled with a fluorescence detector (FLD), whereas it was easily detected in ochratoxigenic A. niger extracts used as positive control. The same outcome was obtained using LC-MS. The presence of other metabolites with retention times similar to the OTA signal in the A. tubingensis extracts or background noise of the growth media may be reasons for the misinterpretation of the chromatograms obtained by HPLC-FLD.