Evaluation of Some Filamentous Fungi for Heavy Metal Tolerance

Abstract

This study investigates the tolerance of various filamentous fungi to heavy metals, aiming to identify potential candidates for bioremediation. Filamentous fungi, due to their robust growth and extensive hyphal networks, are promising organisms for the bioremediation of environments contaminated with heavy metals. About 176 fungal strains were isolated and identified from the contaminated industrial effluents, using micromorphological features all from five different genus; Aspergillus, Penicillium, Byssochlamys, Saccharomyces and Mucor, which demonstrated robust growth in the presence of high concentrations of heavy metals. The isolates were exposed to increasing concentrations (100 to 500 ppm) of Cd, As, and Cr in agar media to assess their tolerance levels. The best mycelial growth was found in Penicillium nalgiovenses on chromium and cadmium (1.060 and 0.917), amended medium respectively, followed by Mucor recemoses (1.012 and 0.868), while the least was in Saccharomyces cerevisae (0.381) on chromium. Key growth parameters, such as radial growth rate and biomass production, were measured to determine the extent of heavy metal tolerance. The best fungus in terms of tolerance index was A. flavus (0.721, 0.640, 0.570, 0.547 and 0.349) for the 100 to 500 ppm respectively. Followed by Byssochlamys nivea (0.648, 0.625, 0.511, 0.477 and 0.398). The findings suggest that filamentous fungi possess significant potential for bioremediation of heavy metal-contaminated environments. Further research into optimizing conditions for their application and understanding the molecular mechanisms of their tolerance could enhance their effectiveness in environmental clean-up efforts.