R4: Mineral sciences of the Earth surface

[R4-11] Precipitation of dolomite induced by halophilic bacteria: influence of Mg2+, Ca2+, and HCO3- concentrations

*Maho Hasegawa¹, Hiromi Konishi¹ (1. Niigata Univ.)

Keywords:disordered dolomite, Microbe-mediated mineralization, Halophiles, Biomineralization

Culture experiments using 8 phylogenetically close halophilic bacteria species were conducted to verify to what extent dolomite precipitates under conditions similar to seawater. The precipitates were dolomite (disordered), aragonite, high Mg calcite, and Monohydrocalcite. No precipitates were produced in the control experiment. This suggests that living or dead bacteria are responsible for carbonate formation. Dolomite precipitation occurred at compositions of HCO₃^- = 50 (mM) and Ca²⁺ : Mg²⁺ = 10:50 to 20:100 (mM).