Fullerol C60(OH)24 nanoparticles modulate aflatoxin B1 biosynthesis in Aspergillus flavus

The water soluble fullerene C-60 daughter product - fullerols C-60(OH)(24) (FNP) possesses a great potential of modifying secondary metabolites biosynthesis. In order to clarify the extent of interaction, the impact of FNP (10, 100 and 1000 ng mL(-1)) on aflatoxin production and the available precursors of biosynthesis pathway from Aspergillus flavus NRRL 3251 was determined, in both the mycelia and yeast extract sucrose (YES) medium, during a 168-hour growth period at 29 degrees C in the dark. The FNP of 8 nm in diameter, and with a zeta potential of -33 mV affected mycelial growth at 1000 ng mL(-1) while conidia production was slightly affected at 10 ng mL(-1). The FNP effect on aflatoxin and it biosynthetic precursors was concentration dependent and alteration of the sterigmatocystin (ST) export from the cell was observed. Most of the monitored aflatoxin precursors, except norsolorinic acid, were detected in both mycelia and YES medium. However, observed precursor concentrations were much higher in mycelia, with exception of ST. The study shows the loss of FNP antioxidative effect after 120 hours of growth, and strong concentration dependent aflatoxigenic effect after that time. Thus, this data is relevant to guide future considerations on FNP-fungal interactions in the environments and on risk assessment.