Mycotoxigenic fungi, OTA and fumonisin B2 production by Aspergillus section Nigri isolated from wine grapes and natural occurrence of OTA in wines of Northern Argentinean Patagonia

Abstract

The Northern Argentinean Patagonia is the southernmost producing region of wine grapes and wine in Argentina. Their wines possess distinctive features due to the wide variety of red and white grapes and weather conditions, achieving great acceptance in local and international markets. The aims of the present study were to determine and characterize the mycobiota present in wine grapes from Northern Patagonia, to analyse the ability of the isolates to produce mycotoxins, and to determine the natural occurrence of OTA and monitoring its presence in wine over time. A wide diversity of fungal contamination was found on grape berries surface. The most abundant genera isolated were: Alternaria (55.8 %), Aspergillus (12.7 %), Trichoderma (6.5 %), Penicillium (5.3 %), Fusarium (4.4 %), Epiccocum (4.2 %), Acremonium (2.6 %) and Botrytis (2.5 %). Alternaria was the predominant genus with the highest proportion during the three years of study and A. tenuissima was the most frequent species isolated. In contrast, a low incidence of Aspergillus section Nigri was found. Isolates identified belonged to Aspergillus niger aggregate and, more specifically, to A. tubingensis species. No Aspergillus carbonarius isolates were found. A low percentage of A. tubingensis isolates were ochratoxin A producers (4.7 %) in the range of 14.6–233.3 μg/Kg and FB2 producers (3.7 %) in the range of 79.7–277.8 μg/Kg. None of the OTA producer isolates were able to produce FB2 and vice versa. Analysis of OTA content in wine samples from Northern Patagonia showed negative results: OTA was not detected in any of the samples analysed. Our findings suggest a low risk of wine contamination with OTA.