Detection of Potentially Toxic Elements and Tolerant Native Fungi Presence in an Urban Stream in Argentina

Potentially toxic elements (PTEs) represent a critical threat to aquatic and terrestrial ecosystems and human health. This study assessed the presence of PTEs and the tolerance capacity of native filamentous fungi inhabiting contaminated freshwater-associated soils. Soil and water samples were collected from four sites along the urban stream (Buenos Aires, Argentina), and PTEs concentrations were quantified. Thirteen fungal isolates were obtained from contaminated soils and characterised using phenotypic traits, while molecular identification was achieved for a subset of isolates through analyses of the internal transcribed spacer (ITS) region and the translation elongation factor 1-alpha (TEF1-α) gene. Probable tolerance to manganese (Mn), zinc (Zn), copper (Cu), lead (Pb), chromium (Cr) and cadmium (Cd) was evaluated on solid media using a tolerance index (TI). All isolates exhibited tolerance to at least one of the tested PTEs. Notably, three Fusarium strains showed tolerance to Pb, with Fusarium equiseti-like IR2.1 and Purpureocillium lavendulum-like MR2.8 exhibiting high tolerance across multiple PTEs. The detection of multi-PTEs tolerance in P. lavendulum-like isolates expand previous evidence largely limited to Cd and underscores the adaptive capacity of native fungal communities in contaminated urban freshwater systems, supporting their future, more detailed evaluation for potential bioremediation applications.