REMEDIATION POTENTIALS OF PB, ZN, AND MN IN MINING IMPACTED WATER BY A NOVEL MN-OXIDIZING FUNGUS FROM TAR CREEK SUPERFUND SITE

Manganese (Mn) oxides are wide-spread minerals in environment that commonly control the uptake and release of other metals through multiple mechanisms. In nature, Mn (II)aq is oxidized by microbial activities to form sparingly soluble nanocrystalline Mn (III/IV) oxides. The high reactivities of biogenic Mn oxides significantly affect the migration of environmental pollutants (especially metals), which play an important role in the biogeochemical cycle of various elements.

Tar Creek superfund site, consisting of lead (Pb) and zinc (Zn) mining areas in northeast Oklahoma, emitted wastewater containing high concentrations of multiple heavy metals and salts. The Pb and Zn are the major concerns in wastewater and become an immense risk for animals and human due to their toxicity. Compared with conventional physico-chemical methods, eco-friendly and cost-effective bioremediation methods represent an opportunity to efficiently remove these co-contaminants. For environmental remediation, myco-genic Mn oxides are of particular importance because diverse Mn-oxidizing fungi can survive in harsh (e.g., metal-rich and saline) environments and are prevalent in many metal-polluted sites.

We have isolated a new fungus (phylogenetic analysis is ongoing) from the Tar Creek wastewater, which is capable to oxidize Mn (II) to form Mn (III/IV) oxides. From the initial result, Pb and Zn showed different effects on the oxidation reaction of Mn. The fungal growth and the subsequent Mn (II) oxidation were inhibited at a high concentration of Pb, indicating the toxicity of high Pb to the fungus. In contrast, the growth of fungi wasn’t inhibited but the oxidation reaction of Mn (II) was inhibited at a high concentration of Zn. This result may be due to the inhibition of Mn oxide-related enzymes by Zn. We are conducting a series of experiments with fungal cultures grown in lab synthetic mining wastewater with various amounts of Mn/Pb/Zn. The elemental and spectroscopic analysis will be combined to determine the metal removal mechanisms. The Mn oxide-related enzymes will be separated using standard native PAGE and identified by LC/MS/MS. Results from this study may reveal a new pathway of biogenic Mn (II) oxidation process and provide insights into the development of a fungal bioreactor for removing metal contaminants from wastewaters.