Precipitation of Low‐Temperature Dolomite From an Anaerobic Microbial Consortium: The Role of Methanogenic Archaea

Precipitation of Low‐Temperature Dolomite From an Anaerobic Microbial Consortium: The Role of Methanogenic Archaea

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  • November 20, 2018
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Here we report precipitation of dolomite at low temperature (30 °C) mediated by a mixed anaerobic microbial consortium composed of dissimilatory iron‐reducing bacteria (DIRB), fermenters, and methanogens. Initial solution geochemistry is controlled by DIRB, but after 90 days shifts to a system dominated by methanogens. In live experiments conditions are initially saturated with respect to dolomite (Ωdol = 19.40) and increase by two orders of magnitude (Ωdol = 2 330.77) only after the onset of methanogenesis, as judged by the increasing [CH4] and the detection of methanogenic micro‐organisms. We identify ordered dolomite in live microcosms after 90 days via powder X‐ray diffraction, while sterile controls precipitate only calcite. Scanning electron microscopy and transmitted electron microscopy demonstrate that the precipitated dolomite is closely associated with cell walls and putative extra‐cellular …

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