Cadmium and Lead Tolerance of Filamentous Fungi Isolated from Contaminated Mining Soils

Heavy metal contamination in soil, especially cadmium (Cd) and lead (Pb), poses serious environmental and health risks, particularly in mining regions. While this contamination affects most organisms present in such areas, some filamentous fungi proliferate and immobilize metals in contaminated areas. In this work, six filamentous fungi tolerant to high concentrations of these metals were identified by macroscopic and microscopic morphological characteristics, as well as molecularly, through conserved regions of internal transcribed spacers (ITSs). Tolerance to Cd and Pb was evaluated in solid and liquid culture media, and half the maximum inhibitory concentration (IC50) was assessed. Pb tolerance was observed in Penicillium simplicissimum, Paecilomyces lilacinus, and Rhizopus microsporus (IC50: 3874, 1176, and 211.80 mg/L). Cd tolerance was also noted in Paecilomyces lilacinus, Fusarium oxysporum, Rhizopus microsporus, and Cunninghamella sp. (IC50: 311, 223, 29.25, and 25.18 mg/L). These findings indicate that these fungi have adopted effective strategies for survival in contaminated environments and emphasize their potential for future applications in the bioremediation of multi-metal-contaminated soils. This research lays the groundwork for exploring tolerance mechanisms and evaluating the efficacy of native fungal isolates in mitigating heavy metal contamination.