Citrobacter sp strain GW-M Mediates the Coexistence of Carbonate Minerals with Various Morphologies
Citrobacter sp strain GW-M Mediates the Coexistence of Carbonate Minerals with Various Morphologies
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DOI：
10.1080/01490451.2013.769650
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发表时间：
2013-09-14
影响因子：
2.3
通讯作者：
Wang, Chao
中科院分区：
文献类型：
--
作者：
Guo, Wenwen;Ma, Heng;Wang, Chao
为了更好地了解微生物形成碳酸盐矿物的机理，采用改良的拉戈阿韦尔梅利亚（LV，a hypersaline coastal Lagoon，Rio de Janeiro，Brazil）培养基（Mg/Ca摩尔比为6：1），在从土壤中分离的菌株GW-M的介导下进行了为期70天的培养实验。结果表明，菌株GW-M可以介导高镁方解石和文石的形成和哑铃形，花椰菜形，菱形和不规则矿物共存的改良LV培养基。随着培养时间的延长，菱形晶体的数量显著增加。这些形成的拟议机制如下。胞外聚合物（EPS）表面总是发生非均匀成核，实验产物在任何阶段都存在不规则形状的碳酸盐。其形态从杆状到哑铃形再到菜花形。在初始阶段（至第20天），细菌分泌的氢离子和EPS仅影响细胞周围的微环境，并且碳酸盐沉淀在细菌细胞表面。在中期和后期（45和70天），微生物及其分泌物影响整个培养基。在此条件下，当发生均匀成核时，形成菱形晶体。此外，能谱分析结果表明，菱面体碳酸盐矿物中Mg含量明显低于其它形状的碳酸盐矿物，但不能仅从菱面体碳酸盐矿物中Mg含量来判断矿物形态与矿物种类之间的关系。这些结果进一步阐明了微生物存在下碳酸盐沉淀的机理。
To better understand the formation mechanism of carbonate minerals by microbes, culture experiments with a duration of 70days were performed under the mediation of strain GW-M isolated from soil using modified Lagoa Vermelha (LV, a hypersaline coastal Lagoon, Rio de Janeiro, Brazil) medium with 6:1 Mg/Ca molar ratio. The results demonstrated that strain GW-M can mediate the formations of both high-Mg calcite and aragonite and that dumbbell-, cauliflower-, rhombohedra-shaped, and irregular minerals coexist in the modified LV medium. The amount of rhombohedra-shaped crystals increased significantly with culture time. A proposed mechanism for these formations is the following. Heterogeneous nucleation on the surface of the extracellular polymeric substances (EPS) always occurred, and carbonates with irregular shape existed in experimental products at any stages. The morphologies evolved from rod to dumbbell and finally to cauliflower. At the initial stage (till day 20), hydrogen ions and EPS secreted by the bacteria only influenced the microenvironment around the cells, and carbonates were precipitated on the surface of bacterial cells. At the middle and late stages (on days 45 and 70), microbes and their secretions influenced the whole medium. Under these conditions, rhombohedra-shaped crystals were formed when homogeneous nucleation occurred. In addition, the results of energy-dispersive spectrometry (EDS) showed that Mg contents in the synthesized carbonate minerals with rhombohedra-shaped were significantly lower than those of carbonates with other shapes, though relationship between morphology and species of mineral cannot be obtained by this phenomenon alone. These results shed further light on the mechanism of carbonate precipitation in the presence of microbes.