Bioaccumulation of toxic metals by fungi of the genus Aspergillus isolated from the contaminated area of Ostramo Lagoons

Abstract

The study compares the ability to bioaccumulate toxic metal ions using microscopic filamentous fungi of the genus Aspergillus isolated from the anthropogenically contaminated site of the Ostramo Lagoons (Ostrava, Czech Republic). The experiment comprised six species of indigenous fungal isolates: A. niger, A. candidus, A. iizukae, A. westerdijkiae, A. ochraceus and A. clavatus. Nutrient liquid media enriched with Cu(II), Zn(II), Ni(II) and Cr(III) were individually inoculated with spores of these fungi. After thirty days of incubation, the content of metal ions in the dried fungal biomass and medium was measured by the AAS. It was found that the average bioaccumulation capacity of selected toxic metal within the tested strains decreases in the following order: A. ochraceus > A. candidus > A. clavatus > A. westerdijkiae > A. iizukae > A. niger. The highest bioaccumulation efficiency was achieved by the A. ochraceus strain which accumulated Cu(II) with an efficiency of 57.42 %, Zn(II) with 56.88 %, Cr(III) with 37.73 %. When comparing the ability of bioaccumulation of the toxic metals, the following was found: Zn(II) > Cu(II) > Cr(III) > Ni(II). Understanding of bioaccumulation processes that take place in fungal cells at the molecular level may lead to better strategies for the application of these interesting microorganisms in bioremediation processes.