Monitoring of ochratoxin A and ochratoxin-producing fungi in traditional salami manufactured in Northern Italy

Fungi have a crucial role in the correct maturation of salami, but special attention should be addressed to the production of thenephrotoxic, immunotoxic, and carcinogenic mycotoxin ochratoxin A (OTA). In a monitoring study conducted in Northern Italy,OTA was detected by liquid chromatography coupled with mass spectrometry in 13 out 133 samples of traditional salami (9.8%of the total count). Mycological analysis of these samples yielded 247 fungal isolates which were identified to species level. Themost frequent species were Penicillium nalgiovense, P. solitum, and P. chrysogenum. P. nordicum, an OTA-producing speciescommonly found in protei naceous foo d, was not found in these samples. Three i so la te s were fou nd to be Aspergilluswesterdijkiae, an OTA-producing species. In order to check the results of the microbiological identification, 19 different strainsof Aspergillus and 94 of Penicillium were tested for the presence of a sequence common to OTA-producing fungi by real-timePCR. None of the studied isolates, including the three A. westerdijkiae, possessed the otanpsPN target which is common to OTA-producing strains. Two out of three isolates of the A. westerdijkiae were also PCR-negative for the otanpsPN gene and did notproduce OTA in culture. Conversely, this target sequence was amplified from the DNA purified from 14 salami casings includingthree casings harboring A. westerdijkiae. The amplification of sequences specific for OTA-producing strains performed on totalgenomic DNA extracted directly from salami casings provided a more suitable approach than PCR analysis of isolates fromsalami for the OTA-related otanpsPN gene to evaluate the risk of OTA contamination.