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Calcium Carbonate Formation in the Presence of Biopolymeric Additives
Published on: May 14, 2019
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Cave bacteria-induced amorphous calcium carbonate formation.
Nóra Tünde Enyedi1, Judit Makk1, László Kótai2,3
1Department of Microbiology, Faculty of Science, Eötvös Loránd University, Pázmány P. sétány 1/C, H-1117, Budapest, Hungary.
Scientific Reports
|May 28, 2020
Summary
Cave bacteria produce stable amorphous calcium carbonate (ACC) shielded by extracellular polymeric substances (EPS). This bacterial ACC is stable in water-rich conditions, unlike lab-made ACC, offering insights into cave biomineralization.
Area of Science:
- Geochemistry
- Microbiology
- Biomineralization
Background:
- Amorphous calcium carbonate (ACC) is a biomineral precursor crucial for crystalline calcium carbonate evolution.
- Bacterial extracellular polymeric substances (EPS) are known to influence mineral formation.
- Cave environments harbor diverse microbial communities that can impact mineral precipitation.
Purpose of the Study:
- To investigate bacterial production of amorphous calcium carbonate (ACC).
- To determine the role of bacterial extracellular polymeric substances (EPS) in stabilizing ACC.
- To assess the stability and characteristics of bacterially produced ACC under environmental conditions.
Main Methods:
- Isolation and culturing of bacterial strains from a Hungarian cave.
- Characterization of bacterial extracellular polymeric substances (EPS) composition.
- Analysis of amorphous calcium carbonate (ACC) formation and stability in the presence of EPS.
Main Results:
- Several bacterial strains isolated from a Hungarian cave produce amorphous calcium carbonate (ACC).
- Bacterial EPS effectively shields ACC from crystallization in water-rich environments at room temperature.
- Bacterial ACC remained stable for at least six months, unlike laboratory-produced ACC.
- EPS composition includes lipids, proteins, carbohydrates, nucleic acids, and notably, long-chain fatty acids, suggesting a micellar encapsulation mechanism.
Conclusions:
- Bacteria are capable of producing stable amorphous calcium carbonate (ACC) in natural, water-rich cave environments.
- Bacterial EPS plays a critical role in preventing ACC transformation into crystalline forms like calcite.
- Bacterially produced ACC may be a significant component (up to 20%) of cave sediments and influences geochemical signals in speleothems.
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