Identification and Fumonisin B₂ Production of Black Aspergilli Isolated from Moldy Dried Fruits

Abstract

Some species of black Aspergilli have been recently found to produce fumonisin B₂ (FB₂). Ten strains belonging to three Aspergillus species isolated from moldy dried fruits, which were found to be contaminated by FB₂ and ochratoxin A, were assessed for FB₂ production on 5% NaCl added Czapek yeast extract agar (5% NaCl CYA) plates and sterilized grape berries. Among them, 4 strains identified as A. niger/A. awamori were found to be able to produce FB₂ on 5% NaCl CYA in the range of 12–22 μg/g (average positive: 17 μg/g) and on grape berries in the range of 0.72–13 μg/g (average positive: 5.1 μg/g), respectively. None of 5 strains identified as A. tubingensis produced detectable amounts of the toxin. These findings indicate that A. niger/A. awamori are responsible for the natural occurrence of FB₂ in dried fruits. This is the first record of freshly isolated A. niger/A. awamori strains producing FB₂ in Japan.