Fungal leaching of important metal oxides
Metal oxides have a wide variety of commercial applications. Many are used as dyes in paints and specialist coloured building materials, including concrete and mortar. Fungal metabolites, such as H+ and organic acids, have been shown to be capable of metal complexation and dissolution of a variety of metal/mineral compounds, but their effects on oxides have not been widely explored. The objective of this work was to investigate the ability of two organic acid-producing fungi (Aspergillus niger and Penicillium simplicissimum) to transform zinc oxide (ZnO), hematite and magnetite (Fe2O3 and Fe3O4), copper oxide (CuO) and calcium oxide (CaO). The results show that zinc and calcium oxides were rapidly solubilized by both fungi, with relatively high concentrations of zinc and calcium being accumulated in the biomass. Copper and the two iron oxides were transformed less effectively but appreciable amounts of the metals were still found in the fungal colony. These results highlight the adverse effects of fungal growth on pigmented and dyed building materials.
Full conference title:
156th Society for General Microbiology