Carbonate formation extracellular deposition

Extracellular deposition Some bacteria and fungi contribute to calcium carbonate precipitation in the bulk phase with CO2 generated in their respiration on organic energy sources. This precipitation is dependent on a circumneutral pH range and an excess of Ca " " in the reactive zone in the bulk phase. The formation of extracellular calcium carbonate from respiratory CO2 formed by heterotrophic bacteria and fungi involves the following sequence of equilibrium reactions or variants thereof ... 

The developing spicules are enclosed in a thin retractile organic membrane which, in larger spicules, occurs as a thicker sheath. Formation of the sheath and the deposition of carbonate are accomplished extracellularly by single cells called sclerocytes. The spicules have one to four rays and each ray is... 

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