Reconsidering the Co-Occurrence of Aspergillus flavus in Spanish Vineyards and Aflatoxins in Grapes

Aspergillus flavus is a xerophilic fungus whose geographical distribution is expected to change due to the current climate change scenario. Grapes are one of the most important crops worldwide, and it is essential to evaluate the risk posed by their contamination with potential mycotoxigenic species. Recently, a few reports have described A. flavus as an emerging contaminant in vineyards, which has led to a discussion on the need to legislate aflatoxin contents in grapes. Using a specific PCR assay, the occurrence of A. flavus was demonstrated in 43 out of 61 grape samples collected from Spanish vineyards. Considering the high incidence observed, the risk of the grapes becoming contaminated with aflatoxin was subsequently evaluated. Aspergillus flavus isolates from grapes can grow in grape-based media under a variety of environmental conditions, but they were unable to produce either aflatoxin B1 (AFB1) or aflatoxin B2 (AFB2) even though their ability to produce these toxins was confirmed in a permissive medium (CYA). These results confirm that climate change is affecting the distribution of mycotoxigenic fungi, thereby increasing the occurrence of A. flavus in vineyards, although the risk of the grapes becoming contaminated with aflatoxin needs to be reconsidered.