Manganese (Mn) oxides are widespread minerals in terrestrial and aquatic environments that commonly control the uptake and release of other metals through multiple mechanisms. In nature, the formation of Mn oxides is largely promoted by microbiological activity through direct enzymatic and/or metabolite (e.g., superoxide)-mediated oxidation of aqueous Mn(II). These biogenic Mn oxides usually exist as highly reactive phyllomanganates with a high capacity to remove other metals from various aqueous environments, highlighting their potentials for bioremediation of multiple metal co-contaminants. Mining and industrial wastewaters with complex water chemistry usually contain multiple metals. Zinc(Zn), an essential element for animals and humans but toxic at excessive concentration, often coexists with Mn(II) in containment environments and can bind to Mn oxides via adsorption and incorporation processes. Previous studies have shown that Zn(II) can inhibit the formation of bacterial Mn oxides by changing the structure of the oxidation-related enzyme (i.e., multi-copper oxidases). It remains unknown if similar inhibition of Mn(II) oxidation by Zn(II) exists in fungal systems. Our current work has observed that when Zn(II) and Mn(II) co-present in wastewaters representing environmentally relevant conditions, the formation of Mn oxides by a newly isolated Mn-oxidizing fungus, <i>Curvularia lunata </i>TC-1, has been inhibited by Zn(II) at a relatively low concentration but the growth of the fungus is not affected. Here, we are conducting a series of experiments to determine the oxidation Mn(II) oxidizing pathways of the fungus TC-1 and how Zn(II) can block biomineralization of Mn oxides. The extracellular metabolite and intracellular Mn oxide-related enzymes will be separated from the fungus growing with or without Zn(II) using standard native PAGE and identified by LC/MS/MS. Results from this study may reveal a new pathway of the biogenic Mn(II) oxidation process which will be informative to advance future metal bioremediation methodologies.

Effects of Zn on biomineralization of manganese oxides by a novel Mn-oxidizing fungus (<i>Curvularia lunata</i> TC-1)

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Effects of Zn on biomineralization of manganese oxides by a novel Mn-oxidizing fungus (Curvularia lunata TC-1)