engleski

In vitro coral biomineralization under relevant aragonite supersaturation conditions

The biomineralization of corals occurs under conditions of high and low supersaturation with respect to aragonite, corresponding to daytime or night‐time period of their growth, respectively. Here, in vitro precipitation of aragonite in artificial seawater was investigated at a high supersaturation, allowing spontaneous nucleation and growth, as well as at a low supersaturation conditions which allowed only the crystal growth on the deliberately introduced aragonite seeds. In either chemical systems soluble organic matrix (SOM) extracted from Balanophyllia europaea (light sensitive) or Leptopsammia pruvoti (light insensitive) was added. The analyses of the kinetic, thermodynamic and microscopic data of aragonite precipitation showed that at high supersaturation the SOMs increased the induction time, did not affect the growth rate and were incorporated within aggregates of nanoparticles. At low supersaturation, the SOMs affected the aggregation of overgrowing crystalline units and did not substantially change the growth rate. From these results we can infer that at high supersaturation conditions the formation of nanoparticles, which is typically observed in the skeleton's early mineralization zone may occur, while at low supersaturation the overgrowth on prismatic seeds observed in the skeleton fiber zone is a predominant process. In conclusion, this research sheds insight on coral skeletogenesis bridging physicochemical (supersaturation) and biological (role of SOM) models.

coral ; biomineralization ; supersaturation ; kinetic ; aragonite

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