Penicillium strains isolated from imported and domestic mould-ripened cheeses were examined for mycotoxin-producing ability by analytical thin layer chromatography and HPLC. 16 of 37 strains of P. roquefortii were able to produce mycophenolic acid in 2 yeast extract-5 sucrose broth (YES). 27 of these strains were isolated from imported blue-veined cheese varieties. Of these 27 strains, only 5 isolates from Roquefort cheese (14.7-55.0μg/ml) and 2 of 5 isolates from Danablu cheese (5.3, 17.7μg/ml) had mycophenolic acid-producing potential in culture at 14deg C. None of the strains examined from Gorgonzola, Stilton and Cambozola cheeses produced mycophenolic acid. In contrast, 9 of 10 P. roquefortii strains from domestic blue-veined cheese were ableto produce 4.1-12.2μg/ml mycophenolic acid. All P. roquefortii strains examined showed the ability to produce roquefortine C. All of 20 strains of P. camembertii isolated from imported and domestic white mould cheeses were able to produce 0.05-6.09μg/ml cyclopiazonic acid in YES broth at 25deg C.
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