Growth and ochratoxin A production of Aspergillus section Nigri isolates from Italian grapes

Ochratoxin A (OTA) is a mycotoxin signalled in wine since 1996. Species belonging to the Nigri section of Aspergilli are those mainly responsible for OTA production in grapes. An in vitro trial was planned to study some Italian isolates of Aspergillus section Nigri; growth rates at different temperatures were investigated, to establish the optimum conditions under which their mycelial growth, and in particular OTA production, is possible. Growth of black Aspergilli starts to be relevant over 10 °C. The highest growth rate was observed for Uniseriate and A. niger aggregate, with an optimal temperature of 30°C and probably higher than 37 °C, respectively. Growth rate of A. carbonarius was consistently lower, but it was confirmed as the key fungus for OTA synthesis. Growth was very similar among isolates, but relevant differences were noticed regarding OTA production.