Fumonisins are mycotoxins associated with cancer and several other serious diseases in humans and animals. Production of the mycotoxins has been reported for over two decades in Fusarium species, but has been reported only recently in strains of Aspergillus niger. In addition, a homologue of the fumonisin biosynthetic gene (FUM) cluster, originally identified in Fusarium verticillioides, has been identified in the genome sequence of A. niger. Here, we examined seven species in Aspergillus Section Nigri that occur on grapes for fumonisin production and presence of the fumonisin biosynthetic gene fum8, which served as a marker for the FUM cluster. Fumonisin B2 (FB2) production was detected in nine of 32 A. niger strains examined, but not in any strains of A. brasiliensis, A. carbonarius, A. foetidus, A. japonicus, A. tubingensis, and A. uvarum that were examined. In addition, PCR and Southern blot analyses provided evidence for the presence of fum8 in 11 A. niger strains but not in strains of the other species examined. These findings indicate that the discontinuity of fumonisin production in grapes isolates of A. niger likely results from absence in some isolates of at least part of the FUM cluster. The results also confirm the taxonomic complexity of A. niger from grapes and provide a possible explanation for previously observed variability in FB2 contamination of grapes and wine.
Full conference title:
7th International Aspergillus Meeting
- Asperfest 7 (2010)