Bio-precipitation of Calcite with Preferential Orientation Induced by Synechocystis sp. PCC6803

Abstract

This article presents a research study on the deposition process of Ca²⁺ induced by Synechocystis sp. PCC6803 in BG11 liquid medium with different Ca²⁺ concentrations and different pH. The changes of Ca²⁺ concentrations were measured by using atomic absorption method and the corresponding dynamical models were studied. Minerals and cells were analyzed by high resolution transmission electron microscope, selected area electron diffraction, scanning electron microscope, energy dispersive X-ray spectroscope, X-ray diffraction. The selected area electron diffraction patterns were analyzed by Digital Micrograph 3.7 software. The result showed that Ca²⁺ concentrations decreased faster in the experimental group. The changes of calcium carbonate precipitation were fitting to an exponential model. PH 7 and Ca²⁺ concentration of 1.5 g/L were most conducive to calcium carbonate precipitation in the corresponding gradient range. The result of high-resolution transmission electron microscopy showed that minerals in the experimental group differed obviously from that of the control group in the surface morphology, but both of them were calcites. It also showed that a certain number of minute calcites adhesion to the outer surfaces of S. PCC6803 cells. The result of scanning electron microscopy displayed that many sunken holes emerged on the surfaces of the prismatic calcium carbonate minerals. The results of X-ray diffraction proved that minerals induced by S. PCC6803 were calcites with preferential orientation. This article discusses the process of carbonate formation and the possible role played by S. PCC6803. It may be useful to further study the mechanism of microbial carbonates deposition in the field of geology.

Keywords:

• different Ca²⁺ concentrations
• dynamical process
• extracellular polymeric substances
• high resolution transmission electron microscopy
• preferential orientation
• Synechocystis sp. PCC6803

Acknowledgments

The authors also express their thank to the standard Synechocystis sp. PCC6803 suppliers, Prof. Xuefeng Lu from Qingdao Institute of Bioenergy and Bioprocess Technology, and Prof. Song Qin from Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences. Huaxiao Yan and Hui Zhao have done a lot of work and are listed as co-first authors.

Additional information

Funding

The work was supported by the National Natural Science Foundation of China (41302079, 41372108, 40972043, 21176145), the National key basic research development program (973 Program)(2012 CB723104), the Specialized Research Fund for the Doctoral Program of Higher Education (20133718130001), the Program for Scientific Research Innovation Team in Colleges and Universities of Shandong Province, SDUST Research Fund (2010KYTD103), Shandong Province Natural Science Foundation (ZR2013DQ005), the Higher Educational Science and Technology Program of Shandong Province (No. J10LC15), the China Postdoctoral Science Foundation (2013M540560, 2014T70659), the Open Project of Key Lab of Marine Bioactive Substance and Modern Analytical Technique, State Oceanic Administration, China (MBSMAT-2012-03), the Scientific and Technological Program of Qingdao (13-1-4-232-jch), the Domestic Visiting Scholar Program for Young Core Teachers in Shandong Universities, Shandong Province, China.