Résumé
The fungus Aspergillus flavus MTCC 873, a non-toxigenic isolate demonstrated its capability to synthesize mycoferritin (MF) upon induction with iron in yeast extract sucrose (YES) medium. The molecular mass, yield, iron and carbohydrate contents of the MF were 440 kDa, 0.015 mg/g of wet mycelia, 0.8 and 30.4%, respectively. Native gel-electrophoresis revealed a band corresponding to dimeric form of equine spleen ferritin (ESF). Subunit analysis by SDS-PAGE revealed a single protein band with an apparent molecular mass of 24 kDa, suggesting similar sized subunits in the structure of apoferritin shell. Immunological cross-reactivity was observed with the anti-fish liver ferritin. Transmission electron microscopy (TEM) revealed an apparent particle size of 100 Å. N-terminal amino acid sequence of MF revealed a sequence of SLPLQDYA, which showed identities with other eukaryotic ferritin sequences. The spectral characteristics (UV/VIS, fluorescence and circular dichroic spectra) were similar to ESF. The fungus, unlike A. parasiticus 255 (non-toxigenic) was incapable of producing aflatoxins, when grown in YES media.