Diversity and ochratoxin A-fumonisin profile of black Aspergilli isolated from grapes in China

Abstract

Aspergillus spp. are a common contaminant of grapes and a major source of mycotoxins. China is the largest producer of grape in the world now, however, the toxigenicAspergillus population on grape in this country is still largely unknown. In this study, a total of 345 strains were isolated from grapes of 13 main grapevine producing regions in China. Based on calmodulin gene sequences, eight species withinAspergillus sectionNigri were identified. Among them,Aspergillus tubingensis (48.7%) was predominant, followed byAspergillus welwitschiae (20.6%) andAspergillus aculeatinus (11%). Average of contamination level was up to 64.19%, and we found the occurrence of sectionNigri species on the surface of fresh grapes was significantly influenced by the climate (P<0.05). The subtropical monsoon climate showed the highest fungal detection rate (72.45%), followed by the temperate monsoon climate (49.82%), and the lowest frequency was found in the temperate continental climate (37.23%). Regarding mycotoxin-producing capacity, 4.4% of the total tested sectionNigri isolates (137) were positive for ochratoxin A (OTA) production and 59.6% were fumonisin B2 (FB2) producers. Of those,Aspergillus carbonarius was the main OTA producer andA. welwitschiae andAspergillus niger were the main FB2 producers with different toxigenic ability. Our results highlight the potential risk of OTA and FB2 contamination byA. carbonarius andA. welwitschiae on grape in China, respectively; management strategies should be considered for preventing and reducing the toxigenicAspergillus and its mycotoxins.