Production of Calcite (Calcium Carbonate) Crystals by Soil Bacteria is a General Phenomenon

Abstract

CERTAIN bacteria form crystals from the solutes in their aqueous environment, and some authors have associated this activity with the extensive deposits of CaCO₃ in such places as the Grand Bahama, in spite of the belief that physicochemical effects, such as rapid changes in pH, salinity and temperature, are responsible^1–4. Drew⁵ isolated a denitrifying bacterium able to form CaCO₃ crystals in liquid media and named it “Bacterium calcis” (later named Pseudomonas calcis⁶). Greenfield⁷ obtained aragonite (another form of CaCO₃) crystals in cultures of Pseudomonas in an artificial seawater medium containing Na₂CO₃ or (NH₄)₂CO₃. Buck and Greenfield reported the same result with marine yeast, and claimed that calcium crystals resulted from the accumulation of calcium deposits on the surface of the cells⁸. McCallum and Guhathakurta⁹ observed calcium carbonate deposition by marine bacteria isolated from Bahama Island sediments, and when these were cultured in different media aragonite crystals formed. Shinano¹⁰ described many marine bacteria able to form crystals in liquid media. Ramos-Cormenzana¹¹ has also reported crystal formation by soil bacteria in solid media. This, together with the knowledge that previous research concerned only marine bacteria in liquid media, stimulated us to investigate crystal formation by soil bacteria cultured on solid media.