Heavy Metals Tolerance Potential of Fungi Species Isolated from Gold Mine Tailings in Ghana

Introduction: Heavy metal contamination has necessitated a less expensive and non-destructive clean-up technique such as mycoremediation. This study aimed to isolate, identify, and evaluate the tolerance of fungi species in different concentrations of heavy metals for their potential use in bioremediation. Materials and Methods: Fungi were isolated by serial dilution and spread plate techniques from gold tailings and their tolerance to different concentrations of As, Cd, Cr, Cu, Pb, Zn (as potential bioremediation candidates) was evaluated. Fungal radial growths were recorded daily over a 14 days’ incubation period to establish their tolerance levels using the Tolerance Index. Results: Five isolated fungi species belonged to the genera Aspergillus, Trichophyton, Rhizopus, Trametes, and Trichoderma. Except for Trichophyton rubrum, the other fungi species were tolerant to all Cr concentrations (0 – 100ppm), but no significant difference was observed in mycelia growth compared to their controls. With high tolerance index ranging from 0.91 to 1.02, Trichoderma viride and Rhizopus oryzae were tolerant to all Cu concentrations (0 – 125ppm). High tolerance was exhibited by Trametes versicolor to Cd at 25 and 50 ppm, and by Rhizopus oryzae at 25 ppm, but no significant difference was found in mycelia growth. Rhizopus oryzae tolerated all As and Pb concentrations with high tolerance index ranging from 0.81 to 1.00. It also tolerated   Zn at 200-600ppm concentration with a tolerance index from 0.80 to 0.91. Conclusion: The selective nature of these fungi species for specific heavy metal tolerance indicates their potential for selective use as effective bioremediative clean up agent of heavy metals contaminated sites.