Mineral formation during bacterial sulfate reduction in the presence of different electron donors and carbon sources

• Electron donors for bacterial sulfate reduction influence mineral formation
• Sulfate reduction with formate favors monohydrocalcite formation
• Sulfate reduction with hydrogen favors Mg-phosphate, baricite, calcite and elemental sulfur formation.
• Sulfate reduction with lactate promotes greigite and elemental sulfur formation
• The presence of certain minerals in marine sediments may offer insight to conditions under which the minerals were formed.

Sulfate-reducing bacteria have long been known to promote mineral precipitation. However, the influence of electron donors (energy sources) and carbon sources on the minerals formed during sulfate reduction is less well understood. An investigation was therefore undertaken to determine how these nutrients affect sulfate reduction by the bacterium Desulfovibrio alaskensis G20 in a marine sediment pore water medium. Monohydrocalcite and a small amount of calcite formed during sulfate reduction with formate as the electron donor; Mg-phosphates and calcite precipitated when hydrogen served as the electron donor and when acetate and dissolved inorganic carbon served as carbon sources; and greigite and elemental sulfur were deposited when lactate was used as the electron donor and carbon source. The experimental results were generally consistent with geochemical modeling, suggesting that it may be possible to predict the processes and conditions during formation of these minerals in natural environments.

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