Microbial Kinetic Controls on Calcite Morphology in Supersaturated Solutions

Abstract

Recognizing microbial imprints in the morphology of calcium carbonate minerals that form in very supersaturated solutions containing a high level of dissolved inorganic carbon (DIC) is challenging. To better define criteria for this purpose, we have analyzed the influence of sulfate-reducing bacterium Desulfovibrio desulfuricans strain G20 on the morphology of calcite in such solutions. G20 does not induce large shifts of pH or alkalinity under these conditions, but its uptake of millimolar sulfate and lactate decreases the number of anhedral crystals and stimulates growth of subhedral spar crystals relative to the abiotic controls. In addition, organic compounds associated with the basal growth medium, purified exopolymeric substances produced by G20 and lypopolysaccharide, stimulate the growth of anhedral crystals and crystals with rounded edges at low supersaturation index (SI) of calcite. The effect of organic compounds is reduced at higher SI, where rhombohedral habits dominate. Our results suggest that the local production and uptake of kinetic inhibitors within microbial biofilms may be an important control on calcite morphology in supersaturated solutions.

Review: geological and experimental evidence for secular variation in seawater Mg/Ca (calcite-aragonite seas) and its effects on marine biological calcification

“…Calcification within these biofilms results from the complex interplay of metabolic and geochemical reactions occurring within and adjacent to the biofilm matrix, often in association with exopolymeric substances (Dupraz and Visscher, 2005;Altermann et al, 2006). The C, O, S, N, and Fe-based reduction-oxidation reactions that form the basis of microbial metabolisms greatly affect the biofilm system's pH, total alkalinity, and dissolved inorganic carbon, and thus [CO 2− 3 ] and CaCO3 of the biofilm's intercellular space, which determines whether calcification will occur (Bosak and Newman, 2005;Dupraz and Visscher, 2005;Visscher and Stolz, 2005;Baumgartner et al, 2006). Simplified examples (Visscher and Stolz, 2005) of such microbial reactions that effectively increase [CO …”

“…dissimilatory nitrate-reduction: Such primary microbial metabolic reactions within the biofilm are moderated by secondary reactions associated with exopolymeric substance (EPS; Reid et al, 2000;Arp et al, 2001;Bosak and Newman, 2005;Dupraz and Visscher, 2005). EPS is an extension of the microbial cell that maintains biofilm structure, establishes chemical microgradients by reducing rates of diffusion, may regulate intercellular processes, and functions to bind cations, elevate HCO − 3 , and nucleate CaCO 3 crystals (Arp et al, 2001;Dupraz and Visscher, 2005).…”

“…The aragonite polymorph is less stable than the calcite polymorph at Earth surface conditions and will thus convert to calcite over relatively short geologic timescales. However, various indicators, such as trace element composition (Mg 2+ , Sr 2+ ), quality of textural preservation, and presence of relic aragonite needles (Grotzinger and Reed, 1983;Brand, 1989;Sandberg, 1984, 1993), have been successfully employed to deduce the precursor mineralogy of micritic carbonates altered in this way.…”

The effects of non-metabolizing bacterial cells on the precipitation of U, Pb and Ca phosphates

“…For example, organic molecules exuded by biofilms widely affect the precipitation of calcite, influencing not only the growth kinetics, but the morphology as well (Mann et al, 1990;Archibald et al, 1996;McGrath, 2001;Meldrum and Hyde, 2001;Braissant et al, 2003;Hammes et al, 2003;Tong et al, 2004;Bosak and Newman, 2005;Dupraz et al, 2009), likely through incorporation effects (Lowenstam and Weiner, 1989). Studies have also shown that various organic molecules widely affect the structure and morphology of a range of minerals, including numerous iron oxides (Châtellier et al, 2001(Châtellier et al, , 2004Larese-Casanova et al, 2010;Perez-Gonzalez et al, 2010), uranyl phosphate (Macaskie et al, 2000), and silica (Williams, 1984).…”

Co-Precipitation of Trace Metals in Groundwater and Vadose Zone Calcite: In Situ stablization of 90 Sr and Other Divalent Metals and Radionuclides in Arid Western DOE Sites

“…This initiated predominantly rhombohedral calcite precipitation (Figure 6) at the same critical saturation state (S critical = 11 to 12) in the B. Pasteurii-inclusive and bacteriafree zone of the AGW, indicating the mineralogy and morphology of CaCO 3 precipitation is not controlled by B. Pasteurii surfaces and organic macromolecule exudates, which will be predominately contained within the dialysis membrane. Calcite formation is more likely to reflect the influence of organic and inorganic species slowing the rate of CaCO 3 precipitation (Kitano and Hood, 1965;Meldrum and Hyde, 2001;Braissant and Verrecchia, 2002;Braissant et al, 2003;Bosak et al, 2004;Bosak and Newman, 2005). Organic and inorganic species can complex with cations and reduce catatonic activity and decrease mineral supersaturation, or poison growth sites on the mineral surface (Meldrum and Hyde, 2001).…”