Characterization and evaluation of the bioremediation potential of Rhizopus microsporus Os4 isolated from arsenic-contaminated soil

The persistent presence of arsenic (As) pollution in soils worldwide poses a significant threat to human and environmental health, highlighting the urgent need for effective remediation strategies. Therefore, this study aims to evaluate the capacity of the Rhizopus microsporus Os4 fungal strain, to remove As from contaminated media in laboratory studies. R. microsporus Os4 was isolated from soils of a recreation area of Concepción del Oro, Zacatecas, México, where As concentrations ranged from 146.56 to 11,233.81 mg Kg⁻¹. Os4 was grown in a culture medium with arsenic V (As(V)), and strain resistance was determined at concentrations up to 15,000 mg L⁻¹. In removal assays using a liquid medium with 7,000 mg L⁻¹, Os4 was capable of reducing 90% of the As(V) concentration after 7 days. To determine whether arsenic has an impact on fungal cell walls, Fourier Transform Infrared Spectroscopy analysis was performed, confirming the presence of functional groups in mycelium cell walls with the ability to facilitate the biosorption of arsenic mycelium cell walls. Scanning Electron Microscopy confirmed surface damage and cell morphology changes a response to cell stress induced by contact with As(V). These findings indicate that R. microsporus Os4 employs a biosorption mechanism on the cell wall for arsenic removal, suggesting its potential application in the bioremediation of arsenic-contaminated soils.