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

Abstract

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 µg 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 µg 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.

Keywords:

• microbiology
• mycology
• mycotoxins–fumonisins
• fruit
• wine

Acknowledgements

This work was supported by EC KBBE-2007-222690-2 MYCORED. The authors thank Vincenzo Ricci and Sabrina Nocerino for their valuable technical assistance.