Biological low pH Mn(II) oxidation in a manganese deposit influenced by metal-rich groundwater
The mechanisms, key organisms, and geochemical significance of biological low-pH Mn(II) oxidation are largely unexplored. Here, we investigated the structure of indigenous Mn(II)-oxidizing microbial communities in a secondary subsurface Mn oxide deposit influenced by acidic (pH 4.8) metal-rich groundwater in a former uranium mining area. Microbial diversity was highest in the Mn deposit compared to the adjacent soil layers and included the majority of known Mn(II)-oxidizing bacteria (MOB) and two genera of known Mn(II)-oxidizing fungi (MOF). Electron X-ray microanalysis showed that romanechite [(Ba,H2O)2(Mn4+,Mn3+)5O10] was conspicuously enriched in the deposit. Canonical correspondence analysis revealed that certain fungal, bacterial, and archaeal groups were firmly associated with the autochthonous Mn oxides. Eight MOB within the Proteobacteria, Actinobacteria, and Bacteroidetes and one MOF strain belonging to Ascomycota were isolated at pH 5.5 or 7.2 from the acidic Mn deposit. Soil-groundwater microcosms demonstrated 2.5-fold-faster Mn(II) depletion in the Mn deposit than adjacent soil layers. No depletion was observed in the abiotic controls, suggesting that biological contribution is the main driver for Mn(II) oxidation at low pH. The composition and species specificity of the native low-pH Mn(II) oxidizers were highly adapted to in situ conditions, and these organisms may play a central role in the fundamental biogeochemical processes (e.g., metal natural attenuation) occurring in the acidic, oligotrophic, and metalliferous subsoil ecosystems.
Citation Information
Publication Year | 2016 |
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Title | Biological low pH Mn(II) oxidation in a manganese deposit influenced by metal-rich groundwater |
DOI | 10.1128/AEM.03844-15 |
Authors | Tsing Bohu, Denise M. Akob, Michael Abratis, Cassandre S. Lazar, Kirsten Küsel |
Publication Type | Article |
Publication Subtype | Journal Article |
Series Title | Applied and Environmental Microbiology |
Index ID | 70173848 |
Record Source | USGS Publications Warehouse |
USGS Organization | National Research Program - Eastern Branch |