Yang Guoguo, Li Fuchun, Wang Yazhi, Ji Chen, Huang Lingjie, Su Zhimeng, Li Xuelin, Zhang Chonghong
College of Resources and Environmental Sciences, Nanjing Agricultural University Nanjing 210095 China
RSC Adv. 2022 Sep 21;12(41):26908-26921. doi: 10.1039/d2ra04254a. eCollection 2022 Sep 16.
The study of CaCO polymorphism is of great significance for understanding the mechanism of carbonate mineralization induced by bacteria and the genesis of carbonate rock throughout geological history. To investigate the effect of bacteria and shear force on CaCO precipitation and polymorphs, biomineralization experiments with strain LV-1 were conducted under the standing and shaking conditions. The results show that LV-1 induced the formation of calcite and vaterite under the standing and shaking conditions, respectively. However, the results of mineralization in the media and the CaCl solution under both kinetic conditions suggest the shear force does not affect the polymorphs of calcium carbonate in abiotic systems. Further, mineralization experiments with bacterial cells and extracellular polymeric substances (EPS) were performed under the standing conditions. The results reveal that bacterial cells, bound EPS (BEPS), and soluble EPS (SEPS) are favorable to the formation of spherical, imperfect rhombohedral, and perfect rhombohedral minerals, respectively. The increase in the pH value and saturation index (SI) caused by LV-1 metabolism under the shear force played key roles in controlling vaterite precipitation, whereas bacterial cells and EPS do not play roles in promoting vaterite formation. Furthermore, we suggest that vaterite formed if pH > 8.5 and SI > 0.8, while calcite formed if pH was between 8.0-9.0 and SI < 0.8. Bacterial cells and BEPS are the main factors affecting CaCO morphologies in the mineralization process of LV-1. This may provide a deeper insight into the regulation mechanism of the polymorphs and morphologies during bacterially induced carbonate mineralization.
碳酸钙多晶型的研究对于理解细菌诱导的碳酸盐矿化机制以及整个地质历史时期碳酸盐岩的成因具有重要意义。为了研究细菌和剪切力对碳酸钙沉淀及多晶型的影响，在静置和振荡条件下对菌株LV - 1进行了生物矿化实验。结果表明，LV - 1在静置和振荡条件下分别诱导形成了方解石和球霰石。然而，在两种动力学条件下，培养基和氯化钙溶液中的矿化结果表明，剪切力对非生物体系中碳酸钙的多晶型没有影响。此外，在静置条件下进行了细菌细胞和胞外聚合物（EPS）的矿化实验。结果显示，细菌细胞、结合态EPS（BEPS）和可溶性EPS（SEPS）分别有利于球形、不完美菱面体和完美菱面体矿物的形成。在剪切力作用下，LV - 1代谢引起的pH值和饱和指数（SI）升高在控制球霰石沉淀中起关键作用，而细菌细胞和EPS在促进球霰石形成方面不起作用。此外，我们认为当pH > 8.5且SI > 0.8时形成球霰石，而当pH在8.0 - 9.0之间且SI < 0.8时形成方解石。细菌细胞和BEPS是LV - 1矿化过程中影响碳酸钙形态的主要因素。这可能为细菌诱导碳酸盐矿化过程中多晶型和形态的调控机制提供更深入的见解。
