Fumonisin B2 production by Aspergillus niger from grapes and natural occurrence in must

Aspergillus niger has been recently found to produce fumonisin B2 (FB2). Thirty-one strains belonging to four Aspergillus species isolated from grape were evaluated for FB2 production on agar plates. Four out of eight strains of A. niger produced FB2 (29-293 mu g g-1). None of the strains of A. uvarum (n = 7), A. tubingensis (8) and A. carbonarius (8) produced detectable amounts of toxin. The capability to produce FB2 was also confirmed by some A. niger strains artificially inoculated on grape berries. Natural occurrence of FB2, at levels of 0.01 and 0.4 mu g ml-1, was found in two samples of must collected in Apulian cellars in 2007. This is the first report of FB2 contamination in must. These findings suggest that there is a potential risk of exposure to FB2 in the grape-wine chain for consumers and that A. niger may represent the major fumonisin-producing species among black Aspergilli occurring on grapes.