title: Influence of initial pH on the precipitation and crystal morphology of calcium carbonate induced by microbial carbonic anhydrase.
abstract: The dynamics of calcium carbonate (CaCO(3)) precipitation induced by microbial intracellular or extracellular carbonic anhydrase (CA) at initial pH 6.0, 6.5, 7.0 and 8.0 were investigated through the gaseous diffusion method. The results indicated that both the intracellular and extracellular CA could promote CaCO(3) precipitation. The Ca(2+) ions in the enzymatic systems at initial pH 8.0 were completely deposited at 48 h, which were respectively 21 h, 15 h and 14 h earlier compared with that at initial pH 6.0, pH 6.5 and pH 7.0, indicating that higher pH favored CaCO(3) precipitation in the experimental pH range, and was beneficial to the catalytic action of microbial CA on CaCO(3) precipitation. In addition, XRD analysis indicated that the CaCO(3) precipitates were mainly calcite crystals in the presence of microbial CA. With increasing deposition time, the crystals gradually changed from prism shape to pyramid-like or irregular polyhedral shape based on FESEM analysis.
authors.affiliation: Institute of Resource Biology and Biotechnology, College of Life Science & Technology, Huazhong University of Science & Technology, Wuhan 430074, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Wei-Shan
authors.initials: WS
authors.lastname: Chen
authors.forename: Peng-Peng
authors.initials: PP
authors.lastname: Zhou
authors.forename: Long
authors.initials: L
authors.lastname: Cao
authors.forename: Long-Jiang
authors.initials: LJ
authors.lastname: Yu
mesh_terms: D002119:Calcium Carbonate / Q000737:chemistry* / Q000378:metabolism*; D002256:Carbonic Anhydrases / Q000378:metabolism*; D011232:Chemical Precipitation; D006863:Hydrogen-Ion Concentration
chemical_list: D002256:Carbonic Anhydrases; D002119:Calcium Carbonate