The occurrence of mycotoxins on grapes poses a high risk for food safety; thus, it is necessary to implement effective prevention methods. In this work, a metagenomic approach revealed the presence of important mycotoxigenic fungi in grape berries, including Aspergillus flavus, Aspergillus niger aggregate species, or Aspergillus section Circumdati. However, A. carbonarius was not detected in any sample. One of the samples was not contaminated by any mycotoxigenic species, and, therefore, it was selected for the isolation of potential biocontrol agents. In this context, Hanseniaspora uvarum U1 was selected for biocontrol in vitro assays. The results showed that this yeast is able to reduce the growth rate of the main ochratoxigenic and aflatoxigenic Aspergillus spp. occurring on grapes. Moreover, H. uvarum U1 seems to be an effective detoxifying agent for aflatoxin B₁ and ochratoxin A, probably mediated by the mechanisms of adsorption to the cell wall and other active mechanisms. Therefore, H. uvarum U1 should be considered in an integrated approach to preventing AFB₁ and OTA in grapes due to its potential as a biocontrol and detoxifying agent.

The presence of mycotoxin-producing Aspergillus species in vineyards is a problem for food safety and the economy. In addition, rising temperatures due to climate change are modifying microbial communities, causing the replacement of some fungal species and the rise of mycotoxins such as aflatoxins. The use of microorganisms as biological control agents (BCAs) is one of the most promising strategies to prevent fungal growth and toxin production. In this study, 513 microorganisms were isolated from organic vineyard soils in different regions of Spain. The 480 bacteria and 33 yeasts isolated were sequentially screened to select those with the most suitable characteristics to be used as BCAs. After identifying 16 isolates meeting all requirements, six bacterial isolates were selected to test their potential to control three relevant toxigenic grape fungi in vitro: A. carbonarius, A. niger and A. flavus. Isolates of Arthrobacter sp., Rhodococcus sp. and Bacillus mycoides showed an excellent ability to reduce the growth and mycotoxin concentration of the above-mentioned fungi and represent potential candidates for further study regarding their possible industrial application as a BCA.

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.

Grapes are frequently contaminated by Aspergillus section Nigri fungi and ochratoxin A (OTA), with A. niger also capable of producing substantial fumonisin B₂ (FB₂) levels. Emerging evidence suggests that aflatoxigenic fungi may eventually replace ochratoxigenic fungi in certain regions due to better adaptation to changes in climatic conditions. However, research on the toxigenic fungal community and mycotoxins in grapes from organic vineyards remains limited. Research on Spanish conventional grapes is also deficient, with most of the available literature being outdated. The present study investigates the diversity of toxigenic fungi and the presence of mycotoxins in organically cultivated grape berries in Spain, which are renowned for their significant oenological tradition. This study employed species-specific PCR protocols for fungal characterization and optimized methods for the analysis of OTA, FB₂, and aflatoxin B₁ (AFB₁) by UPLC–ESI–MS/MS. The most prevalent species present were Aspergillus flavus, A. niger, A. parasiticus, A. steynii, A. carbonarius, and A. westerdijkiae (67.1%, 43.5%, 20.0%, 14.1%, 14.1%, and 11.8% of the samples, respectively). OTA was detected only in 16 samples (19%), averaging 0.48 ng/g and peaking at 0.7 ng/g, which were lower than previously reported for conventional grapes. There was no FB₂ or AFB₁ detected. This study is pioneering in its exploration of the occurrence of toxigenic mycobiota, beyond Nigri fungi, and subsequent potential for other serious mycotoxins to contaminate Spain’s organic grapes.