An indigenous lead-tolerant fungal strain was isolated from lead-contaminated soil and identified as Aspergillus niger, via 18S rRNA gene sequencing. We determined the adsorption and accumulation of Pb(II) by living A. niger and the adsorption of Pb(II) via modified A. niger. This strain resisted and removed 96.21%-100% Pb(II) ranging from 2 to 8 mmol/L Pb(II). Pb-containing particles were observed outside of the cell, and lead was detected inside the cell under scanning electron microscopy and transmission electron microscopy. The process of measuring the adsorption ability of modified fungal biomass, freeze-dried, high-temperature, and alkali-treated fungal samples was analyzed; they adsorbed 25.02%, 8.76%, and 15.05% Pb(II) under 8 mmol/L Pb(II) in 43, 10, and 10 hr, respectively. These three types of modified A. niger fit the pseudo-second-order model equation well. PRACTITIONER POINTS: Isolation and identification of effective Pb(II) removal strain from the soil around Dexing lead-zinc mine. The ability of living and modified Aspergillus niger to remove Pb(II) in an aqueous environment was evaluated. Lead distributions inside and outside the cell were analyzed by SEM and TEM. Kinetic models for modified biomass adsorbing Pb(II) were made for describing adsorption process.
Keywords: Aspergillus niger; lead ion; living biomass; modified biomass; removal.
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