Ochratoxin A Production and AFLP Analysis of Aspergillus carbonarius, Aspergillus tubingensis, and Aspergillus niger Strains Isolated from Grapes in Italy.

Ochratoxin A is a potent nephrotoxin and a possible human carcinogen that can contaminate various agricultural products, including grapes and wine. The capability to produce ochratoxin A by species other than A. carbonarius, within Aspergillus Section Nigri, from grapes is uncertain, since strain identification is based primarily on morphological traits. We used AFLPs and genomic DNA sequences (rDNA, calmodulin and ²-tubulin) to identify 77 black aspergilli isolated from grape berries collected in a two-year survey in sixteen vineyards throughout Italy. Four main clusters were distinguished and they shared an AFLP similarity of < 25%. Twenty-two of 23 strains of A. carbonarius produced ochratoxin A (6 to 7,500 ¼g/l), five of 20 strains of A. tubingensis produced ochratoxin A (4 to 130 ¼g/l), three of 15 strains of A. niger produced ochratoxin A (250 to 360 ¼g/l); and none of the 19 strains of Aspergillus “uniseriate” produced ochratoxin A above the level of detection (4 ¼g/l). These findings indicate that A. tubingensis is able to produce ochratoxin A, occurs in grapes and that together with A. carbonarius, and A. niger may be responsible for the ochratoxin contamination of wine in Italy.