Bacteria-Mediated Synthesis of Metal Carbonate Minerals with Unusual Morphologies and Structures

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• 作者：Long Chen ; Yuhua Shen ; Anjian Xie ; Bei Huang ; Rong Jia ; Ruiyong Guo ; Wenzhong Tang
• 刊名：Crystal Growth & Design
• 出版年：2009
• 出版时间：February 4, 2009
• 年：2009
• 卷：9
• 期：2
• 页码：743-754
• 全文大小：569K
• 年卷期：v.9,no.2(February 4, 2009)
• ISSN：1528-7505

文摘

In this paper, well-defined vaterite hollow spheres and amorphous barium carbonate microrods are synthesized in Proteus mirabilis/urea solution. The urease-generated bacterium Proteus mirabilis is able to convert urea to ammonia and CO₂, thereby leading to the precipitation of metal carbonate in Proteus mirabilis/urea solution containing Ca²⁺ or Ba²⁺ ions. It is found that the vaterite hollow spheres are so-called mesocrystals because they have identified primary particles and single-crystalline nature. Crystallization of CaCO₃ using Proteus mirabilis and other two bacteria Bacillus subtilis and Aerobacter aerogenes in dilute ammonia aqueous solutions (pH 8.5) is also investigated, suggesting that the products are all CaCO₃ mesocrystals. Therefore, we speculate that bacteria promoting formation of CaCO₃ mesocrystals may be a common phenomenon. In addition, marked morphological changes and structural transition in the CaCO₃ particles from amorphous calcium carbonate irregular aggregates to vaterite hollow spheres to a mixture of calcite and vaterite hollow discs and polyhedrons in Proteus mirabilis/urea solution are observed depending on the reaction time. BaCO₃ particles change from oval to rod in morphology within 7 days of reaction, but the structure of them is still amorphous even after a month. The biomolecules mainly proteins secreted by the bacteria are probably responsible for the morphologies and structures of metal carbonate minerals by first stabilizing their nanosized precursors, which then transform into mesocrystals or amorphous aggregates via oriented or nonoriented aggregation of nanoparticles. This provides a novel and facile way for the study of biomineralization mechanisms and crystal growth modification.