Biological low pH Mn(II) oxidation in a manganese deposit influenced by metal-rich groundwater

Applied and Environmental Microbiology
By: , and 

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Abstract

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 ProteobacteriaActinobacteria, 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.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Biological low pH Mn(II) oxidation in a manganese deposit influenced by metal-rich groundwater
Series title Applied and Environmental Microbiology
DOI 10.1128/AEM.03844-15
Volume 82
Issue 10
Year Published 2016
Language English
Publisher American Society for Microbiology
Contributing office(s) National Research Program - Eastern Branch
Description 13 p.
First page 3009
Last page 3021
Online Only (Y/N) N
Additional Online Files (Y/N) N