title: Fungal mn oxides supporting Mn(II) oxidase activity as effective Mn(II) sequestering materials.
abstract: We examined the Mn(II)-oxidizing ability of the biogenic Mn oxide (BMO) formed in cultures ofa Mn(II)-oxidizing fungus, Acremonium strictum strain KR21-2. The newly formed BMO effectively sequestered dissolved Mn(II) mainly by oxidizing Mn(II) to insoluble Mn under air-equilibrated conditions, and this ability lasted for at least 8 days. Deaerating the BMOs, poisoning them with NaN3, or heating them all readily weakened their Mn(II) oxidation ability, indicating the involvement of enzymatic Mn(II) oxidation. There was no Mn(II)-oxidizing ability observed for mycelia cultivated without Mn(II) or for residual mycelia after the BMO phase was dissolved, suggesting the need for the oxide phase. A sodium dodecyl sulphate-polyacrylamide gel electrophoresis assay demonstrated that the oxide phase embeds the Mn(II) oxidase and thereby maintains the enzymatic activity in BMOs. Freezing at -80 degrees C preserved the Mn(II)-oxidizing ability in BMOs for at least 4 weeks, while lyophilization caused a complete loss of this ability. Based on these results, we propose that fungal Mn oxides supporting Mn(II) oxidase activity are an effective Mn(II)-sequestering material capable of oxidizing Mn(II) continuously from solutions containing no additional nutrients to maintain biological activity.
authors: Department of Environmental Health Sciences, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan.
authors: Jianing
authors: J
authors: Chang
authors: Department of Environmental Health Sciences, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan.
authors: Yukinori
authors: Y
authors: Tani
authors: Department of Environmental Health Sciences, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan.
authors: Hirotaka
authors: H
authors: Naitou
authors: Department of Biological Environment, Akita Prefectural University, Akita, Japan.
authors: Naoyuki
authors: N
authors: Miyata
authors: National Institute for Environmental Studies, Tsukuba, Japan.
authors: Haruhiko
authors: H
authors: Seyama
mesh_terms: D000164:Acremonium / Q000201:enzymology* / Q000378:metabolism; D004789:Enzyme Activation; D008345:Manganese / Q000378:metabolism*; D017895:Manganese Compounds / Q000378:metabolism*; D010087:Oxides / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism*
chemical_list: D017895:Manganese Compounds; D010087:Oxides; D008345:Manganese; C027424:manganese oxide; D010088:Oxidoreductases