Modeling of rare earth element sorption to the Gram positive Bacillus subtilis bacteria surface
Modeling of rare earth element sorption to the Gram positive Bacillus subtilis bacteria surface
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DOI：
10.1016/j.jcis.2013.09.037
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发表时间：
2014-01-01
影响因子：
9.9
通讯作者：
Takahashi, Yoshio
中科院分区：
文献类型：
--
作者：
Martinez, Raul E.;Pourret, Olivier;Takahashi, Yoshio
在本研究中，使用多位点朗缪尔等温线模型以及线性规划回归方法（LPM）对革兰氏（+）细菌表面上的稀土元素（REE）结合常数和位点浓度进行量化，应用于拟合实验稀土元素吸附数据。该方法在革兰氏+枯草芽孢杆菌表面上发现了一个离散的 REE 结合位点，pH 范围为 2.5-4.5。在 B 的最高生物量浓度为 1.3 g/L 时，这些细菌上 j 位点的平均 log(10) REE 结合常数范围为轻 REE（LREE：La 到 Eu）为 1.08 +/- 0.04 至 1.40 +/- 0.04，重 REE（HREE：Gd 到 Lu）为 1.36 +/- 0.03 至 2.18 +/- 0.14。枯草芽孢杆菌。对于 0.39 和 0.67 g/L 的细菌浓度，获得了类似的值，表明 REE 吸附常数对生物量浓度的独立性。在本研究的实验 pH 范围内，枯草芽孢杆菌对轻稀土元素（例如 La、Ce、Pr、Nd）具有较低的亲和力，而对重稀土元素（例如 Tm、Yb、Lu）具有较高的亲和力，表明重稀土元素在革兰氏+细菌的表面富集。对于 LREE 和 HREE，观察到细菌的总表面结合位点浓度分别为 6.73 +/- 0.06 至 5.67 +/- 0.06 和 5.53 +/- 0.07 至 4.54 +/- 0.03 mol/g，Y 除外，其显示总位点浓度为 9.53 +/- 0.03，log K-REEj 为 1.46 +/-生物质含量为 1.3 g/L 时为 0.02。这些值的差异（例如，LREE 的亲和力较低且结合位点浓度增加，而 HREE 则相反）表明低 pH 条件下 LREE 和 HREE 与革兰氏+细菌反应表面的结合模式之间存在差异。这进一步意味着 HREE 可能在细胞表面结合多个单质子反应基团。多位点 Langmuir 等温线方法与 LPM 回归方法一起，无需事先了解细胞表面 REE 络合位点的数量或浓度，就能够区分革兰氏+枯草芽孢杆菌表面上 LREE 和 HREE 的吸附常数和结合位点浓度模式。这种方法量化了细菌表面 Tm、Yb 和 Lu 的富集，因此被证明是研究控制自然环境中 REE 分配的天然活性吸附剂材料的有用工具。 (C) 2013 Elsevier Inc. 保留所有权利。
In this study, rare earth element (REE) binding constants and site concentration on the Gram(+) bacteria surfaces were quantified using a multi-site Langmuir isotherm model, along with a linear programming regression method (LPM), applied to fit experimental REE sorption data. This approach found one discrete REE binding site on the Gram+ Bacillus subtilis surface for the pH range of 2.5-4.5. Average log(10) REE binding constants for a site j on these bacteria ranged from 1.08 +/- 0.04 to 1.40 +/- 0.04 for the light REE (LREE: La to Eu), and from 1.36 +/- 0.03 to 2.18 +/- 0.14 for the heavy REE (HREE: Gd to Lu) at the highest biomass concentration of 1.3 g/L of B. subtilis bacteria. Similar values were obtained for bacteria concentrations of 0.39 and 0.67 g/L indicating the independence of REE sorption constants on biomass concentration. Within the experimental pH range in this study, B. subtilis was shown to have a lower affinity for LREE (e.g. La, Ce, Pr, Nd) and a higher affinity for HREE (e.g. Tm, Yb, Lu) suggesting an enrichment of HREE on the surface of Gram+ bacteria. Total surface binding site concentrations of 6.73 +/- 0.06 to 5.67 +/- 0.06 and 5.53 +/- 0.07 to 4.54 +/- 0.03 mol/g of bacteria were observed for LREE and HREE respectively, with the exception of Y, which showed a total site concentration of 9.53 +/- 0.03, and a log K-REEj of 1.46 +/- 0.02 for a biomass content of 1.3 g/L. The difference in these values (e.g. a lower affinity and increased binding site concentration for LREE, and the contrary for the HREE) suggests a distinction between the LREE and HREE binding modes to the Gram+ bacteria reactive surface at low pH. This further implies that HREE may bind more than one monoprotic reactive group on the cell surface. A multisite Langmuir isotherm approach along with the LPM regression method, not requiring prior knowledge of the number or concentration of cell surface REE complexation sites, were able to distinguish between the sorption constant and binding site concentration patterns of LREE and HREE on the Gram+ B. subtilis surface. This approach quantified the enrichment of Tm, Yb and Lu on the bacteria surface and it has therefore proven to be a useful tool for the study of natural reactive sorbent materials controlling REE partitioning in the natural environment. (C) 2013 Elsevier Inc. All rights reserved.