Diversity of Aspergillus section Nigri species from vineyards with different agro-climatic conditions in Catalonia, Spain

A few Aspergillus section Nigri species are involved in the ochratoxin A (OTA) contamination in grapes worldwide, and its occurrence is determined by the agro-climatic conditions of each region. The aim of this study was to examine the diversity of black aspergilli isolated from grapes, soil, and air from vineyards with different agro-climatic conditions. A total of four vineyards located in Catalonia were studied. Two grape varieties were sampled at harvesting time during two consecutive years, and soil and air samples were collected from the same vineyards along the four seasons. The occurrence of black aspergilli was higher in grapes than in soil and air samples. In soil, black aspergilli counts were relatively stable throughout the year, being higher in acidic soil. Seasonal fluctuations were seen in air samples, with higher counts in autumn. In all samples, the A. niger aggregate was the predominant group, followed by A. carbonarius and uniserate species. Agro-climatic factors influenced the distribution of black aspergilli species. A high occurrence of A. carbonarius was found in grapes from vineyards with high temperature and humidity whereas its occurrence in soil and air was very low. In the northern vineyard, A. brasiliensis was predominant in grapes and soil. In southern vineyards, A. welwitschiae was predominant in soil while A. tubingensis predominated in grapes and air. Within uniseriate species, we described for the first time the isolation of A. trinidadensis from grapes. All A. carbonarius isolates and three isolates identified as A. welwitschiae were able to produce OTA.