The incorporation of Mg2+ ions into aragonite during biomineralization: Implications for the dolomitization of aragonite

作者：Zuozhen Han, Ruirui Meng, Hui Zhao, Xiao Gao, Yanyang Zhao, Yu Han, Fang Liu, Maurice E. Tucker, Jiarong Deng, Huaxiao Yan · 发表于：Frontiers in Microbiology · 年份：2023 · DOI：10.3389/fmicb.2023.1078430 · 被引用次数：19 · 研究领域：Calcium Carbonate Crystallization and Inhibition、Bone Tissue Engineering Materials、Paleontology and Stratigraphy of Fossils

Bacteria can facilitate the increase of Mg 2+ content in biotic aragonite, but the molecular mechanisms of the incorporation of Mg 2+ ion into aragonite facilitated by bacteria are still unclear and the dolomitization of aragonite grains is rarely reported. In our laboratory experiments, the content of Mg 2+ ions in biotic aragonite is higher than that in inorganically-precipitated aragonite and we hypothesize that the higher Mg content may enhance the subsequent dolomitization of aragonite. In this study, biotic aragonite was induced by Bacillus licheniformis Y 1 at different Mg/Ca molar ratios. XRD data show that only aragonite was precipitated in the media with Mg/Ca molar ratios at 6, 9, and 12 after culturing for 25 days. The EDS and atomic absorption results show that the content of Mg 2+ ions in biotic aragonite increased with rising Mg/Ca molar ratios. In addition, our analyses show that the EPS from the bacteria and the organics extracted from the interior of the biotic aragonite contain the same biomolecules, including Ala, Gly, Glu and hexadecanoic acid. The content of Mg 2+ ions in the aragonite precipitates mediated by biomolecules is significantly higher than that in inorganically-precipitated aragonite. Additionally, compared with Ala and Gly, the increase of the Mg 2+ ions content in aragonite promoted by Glu and hexadecanoic acid is more significant. The DFT (density functional theory) calculations reveal that the energy needed for Mg 2+ ion incorporation int...