This study investigated the CaCO
3 spontaneous precipitation in the presence of soluble organic macromolecules (SOMs) extracted from the skeleton of Mediterranean colonial coral species, symbiotic
Cladocora caespitosa (SOM-CCA) and asymbiotic
Astroides calycularis (SOM-ACL). This approach was used as a model to explore
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This study investigated the CaCO
3 spontaneous precipitation in the presence of soluble organic macromolecules (SOMs) extracted from the skeleton of Mediterranean colonial coral species, symbiotic
Cladocora caespitosa (SOM-CCA) and asymbiotic
Astroides calycularis (SOM-ACL). This approach was used as a model to explore biomineralization processes in marine organisms. The research was conducted in systems without or with the addition of Mg
2+ (Mg/Ca molar ratio was 5:1) and/or SOMs (concentration range was 0.5–4 ppm). In the model system (system without Mg
2+ or SOMs), only vaterite spherulites precipitated, while in the system with added Mg
2+, only aragonite irregular aggregates were observed. Although the addition of SOMs did not influence the polymorphic composition of the CaCO
3 precipitates, it led to noticeable changes in induction time and morphology of CaCO
3 crystals, and these effects were stronger in the presence of SOM-ACL. By comparing systems containing both Mg
2+ and SOM with the model system as well as with systems where Mg
2+ or SOMs were added individually, the dominant role of Mg
2+ in the aragonite formation was observed. However, the combined effect of Mg
2+ and both SOMs enhanced the inhibition of CaCO
3 precipitation. This inhibitory effect was particularly enhanced in the system combining Mg
2+ and SOM-ACL.
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