Influences of fibrous clay particles on Aspergillus niger bioactivity and Pb(Ⅱ) removal efficiency

This study investigates the influences of palygorskite on the lead (Pb) removal with involvement of Aspergillus niger ( A. niger ). A. niger exhibited high Pb removal efficiency (>97%) via oxalic acid-mediated biomineralization. Meanwhile, the fungus remained active even under high 500 mg/L Pb. This was attributed to the reduced Pb bioavailability through biomineralization and toxicity dilution via biomass proliferation. The addition of palygorskite enhanced Pb removal by providing nucleation sites. In addition, transcriptomic results indicated that Pb stress upregulated genes related to the TCA cycle, glycolysis, and oxalic acid biosynthesis. Palygorskite further amplified the expression of these key genes. These findings confirm that palygorskite promotes A. niger -mediated Pb biomineralization, highlighting the remediation potential of this fungus-mineral system. This study proposed the complex environmental interactions among fibrous clay, microorganisms and heavy metals