Efficient immobilization behavior and mechanism investigation of Pb(II) by Aspergillus tubingensis

Abstract

Objectives: To understand the mechanism of Pb(II) immobilized by Pb(II)-tolerant microbes.

Results: Aspergillus tubingensis isolated from the lead-zine mine was investigated through surface morphology observation and multiple experimental analysis in order to elucidate the Pb(II) biosorption and immobilization behavior. The maximum Pb(II) uptake capacity of A. tubingensis was about 828.8 mg L^-1. Fourier transform-infrared spectra and environmental scanning electron microscope indicated that a large number of functional groups (carboxyl, phosphoryl and sulfydryl, etc.) participated in Pb(II) binding on the cell surface. Raman and X-ray diffraction, field emission high-resolution transmission electron microscopy and X-ray absorption fine structure investigation revealed that the Pb(II) loaded on the surface of the fungus could be transformed into PbCO₃ and PbS nanocrystals. Meanwhile, Pb(II) transported into the cell would be oxidized to form lead oxide minerals (Pb₂O_3.333) over time.

Conclusions: This study has important implications for an in-depth understanding of Pb(II) removal by A. tubingensis and provides guidance for remediating lead-polluted environment using microorganisms.

Keywords: Bioaccumulation; Bivalent lead; Fungi.