Calcium carbonate precipitation and crystal morphology induced by microbial carbonic anhydrase and other biological factors

The effect of microbial carbonic anhydrase (CA) on the calcium carbonate (CaCO3) precipitation was systematically investigated comparing to other biological factors (bovine CA, bovine serum albumin, carboxymethyl chitosan and glutamic acid). The results showed that the precipitation rate of Ca2+ in the presence of either microbial CA or bovine CA was faster than that in the presence of 1% bovine serum albumin, 1% carboxymethyl chitosan or 1% glutamic acid, respectively. In addition, XRD analysis indicated that the dominant CaCO3 crystal phase was calcite. The CaCO3 crystal morphologies mainly showed cubic and polyhedral shapes induced by microbial CA, and became multiformity induced by other factors from FE-SEM analysis. These results suggested a novel approach for biomimetic synthesis of CaCO3 materials by microbial CA.