title: Precipitation of calcite induced by Synechocystis sp. PCC6803.
abstract: Calcite with laminate structure was successfully prepared by culturing Synechocystis sp. PCC6803 with different concentrations of calcium chloride (CaCl₂) in BG11 media. S. PCC6803 was examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), laser confocal scanning microscope (LCSM) and energy dispersive spectroscopy (EDS). The effects of Ca²⁺ concentrations and pH values on calcification were investigated and the micro morphs of the CaCO₃ crystals were observed by means of SEM. These results showed that CaCO₃ crystals could be more easily formed with increasing the concentration of CaCl₂ in S. PCC6803 culture solution. S. PCC6803 could largely bind calcium ions, most of which were present in extracellular polymeric substances and on the cell wall. Inside the cells there were a lot of circular areas rich in calcium ions without the crystallization of calcium. Some cells produced a thicker gelatinous sheath outside of the translucent organic thin layer. And the cells inside also produced major changes that the original chloroplasts were almost transformed into starch grains whose sizes were from 0.5 to 1 μm with relatively uniform in sizes. At the same time the cell sizes significantly reduced to only about 8-9 μm almost changing to half of its original diameters. The calcite crystals with a highly preferred orientation induced by S. PCC6803 were observed with X-ray diffraction (XRD). A critical implication was that S. PCC6803 could induce bio-calcification and then mediate the further growth of CaCO₃ crystals in the biological system.
authors.affiliation: Shandong Provincial Key Lab of Depositional Mineralization and Sedimentary Minerals, College of Geological Science and Engineering, Shandong University of Science and Technology, Qingdao, 266590, People's Republic of China.
authors.forename: Zuozhen
authors.initials: Z
authors.lastname: Han
authors.forename: Huaxiao
authors.initials: H
authors.lastname: Yan
authors.forename: Shixue
authors.initials: S
authors.lastname: Zhou
authors.forename: Hui
authors.initials: H
authors.lastname: Zhao
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Ningning
authors.initials: N
authors.lastname: Zhang
authors.forename: Chuankai
authors.initials: C
authors.lastname: Yao
authors.forename: Lin
authors.initials: L
authors.lastname: Zhao
authors.forename: Chunyan
authors.initials: C
authors.lastname: Han
mesh_terms: D002119:Calcium Carbonate / Q000737:chemistry* / Q000378:metabolism*; D002122:Calcium Chloride / Q000378:metabolism*; D011232:Chemical Precipitation; D003460:Crystallization; D003470:Culture Media / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D013052:Spectrometry, X-Ray Emission; D046939:Synechocystis / Q000378:metabolism* / Q000648:ultrastructure; D014961:X-Ray Diffraction
chemical_list: D003470:Culture Media; D002119:Calcium Carbonate; D002122:Calcium Chloride
references.citation: Curr Opin Biotechnol. 2010 Jun;21(3):365-71
references.pmid: 20456936
references.citation: Biochemistry. 1989 Jan 10;28(1):339-45
references.pmid: 2706258
references.citation: J Struct Biol. 2001 Apr;134(1):56-66
references.pmid: 11469877
references.citation: Biomaterials. 2000 Feb;21(3):213-22
references.pmid: 10646937
references.citation: Appl Environ Microbiol. 2003 Aug;69(8):4901-9
references.pmid: 12902285
references.citation: Biomaterials. 2004 Aug;25(17):3923-9
references.pmid: 15020169