Bioaccumulation of chromium by Fusarium oxysporum

Abstract

We investigated the impact of both hexavalent and trivalent chromium on mycelial growth and metal accumulation in the wilt pathogen of tomato (Fusarium oxysporum f. sp. lycopersici). Experiments were conducted in liquid growth medium amended with 19 concentrations of either Cr(III) or Cr(VI). Metal-amended medium was inoculated with the pathogen and incubated for 15 days at 25 ± 3 ° C, 50 rpm, and at pH 5. Generally, the fungal dry biomass was significantly inhibited by 14-64% and 30-95% with increase in concentrations (5-350 ppm) of Cr(III) and Cr(VI), respectively. The fungus was unable to grow at metal concentrations higher than 400 ppm. The metal accumulation by the fungus decreased with an increase in metal concentration. The fungal biomass exhibited the greater accumulation capacity (0.01-2.6 mg/g) for Cr(VI) than that of Cr(III) (0.01-1.86 mg/g). The bioaccumulation factor of the fungus for both oxidation states of Cr ranged between 0.7 and 0.9.