Catalytic Biomineralization of Fluorescent Calcite by the Thermophilic Bacterium Geobacillus thermoglucosidasius

The thermophilic Geobacillus bacterium catalyzed the formation of 100-mu m hexagonal crystals at 60 degrees C in a hydrogel containing sodium acetate, calcium chloride, and magnesium sulfate. Under fluorescence microscopy, crystals fluoresced upon excitation at 365 +/- 5, 480 +/- 20, or 545 +/- 15 nm. X-ray diffraction indicated that the crystals were magnesium-calcite in calcite-type calcium carbonate.