IMPACT OF BUFFERS ON MYCOGENIC MANGANESE OXIDE FORMATION
Using a combination of X-ray diffraction, Fourier-transform infrared spectroscopy, and extended X-ray absorption fine structure spectroscopy, we are investigating the structures of Mn oxides produced during Mn oxidation by four Mn(II)-oxidizing Ascomycete fungi species in a buffer-free flow-through system and in closed- and flow through-systems buffered by HEPES or carbonate. We find that the buffer type affects fungal growth behaviors as well as Mn oxide production, with specific effects distinct for each species. For example in a calcium carbonate buffer, Stagonospora sp. SRC1lsM3a grows and oxidizes Mn(II) faster than in HEPES buffer which has traditionally been used by most studies of bacteriogenic and mycogenic Mn oxide formation. In addition, the effect of rehydration, to mimic wet and dry cycles, will be discussed. These results highlight the importance of in situ research under conditions that closely mimic natural systems to better constrain our understanding of the impact and fate of contaminants and nutrients in the environment.
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