Cd adsorption onto Pseudomonas putida in the presence and absence of extracellular polymeric substances
Cd adsorption onto Pseudomonas putida in the presence and absence of extracellular polymeric substances
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DOI：
10.1016/j.gca.2008.09.014
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发表时间：
2008-12
影响因子：
5
通讯作者：
M. Ueshima;Brian R. Ginn;E. Haack;J. Szymanowski;J. Fein
中科院分区：
文献类型：
--
作者：
M. Ueshima;Brian R. Ginn;E. Haack;J. Szymanowski;J. Fein
通过研究革兰氏阴性细菌恶臭假单胞菌（Pseudomonas putida）在生物质材料中酶法去除 EPS 和未酶法去除 EPS 的情况下对 Cd 的吸附情况，确定了细菌胞外聚合物 (EPS) 在金属吸附中的作用。使用一系列实验方法来表征 Cd 吸附反应，包括本体质子和 Cd 吸附测量、FTIR 光谱和荧光显微镜。含有 EPS 的生物质样品的质子反应性与不含 EPS 的生物质样品的质子反应性没有显着差异。同样，根据作为 pH 函数进行的大量 Cd 吸附测量，EPS 的存在不会显着影响质量归一化的生物质从溶液中去除 Cd 的程度，也不会强烈影响 FTIR 观察到的 Cd 结合基团。然而，荧光显微镜表明，Cd 虽然集中在细胞壁上，但也在一定程度上与 EPS 结合。总之，这项研究的结果表明，恶臭假单胞菌 EPS 可以结合溶液中高浓度的 Cd，并且结合的性质和质量标准化程度与细胞壁的结合相似。因此，相对于不含 EPS 的系统，含有 EPS 的系统并未表现出增强的质量归一化从溶液中去除 Cd 的能力。 EPS 的存在有效地增加了暴露于 Cd 水溶液的细胞的活力，这可能是由于 Cd-EPS 结合将 Cd 隔离在细胞之外。
The role of bacterial extracellular polymeric substances (EPS) in metal adsorption was determined by studying Cd adsorption onto the gram-negative bacterial species Pseudomonas putida with and without enzymatic removal of EPS from the biomass material. A range of experimental approaches were used to characterize the Cd adsorption reactions, including bulk proton and Cd adsorption measurements, FTIR spectroscopy, and fluorescence microscopy. The proton-reactivities of the biomass samples with EPS are not significantly different from those obtained for EPS-free biomass. Similarly, the presence of EPS does not significantly affect the extent of Cd removal from solution by the biomass on a mass-normalized basis, based on bulk Cd adsorption measurements conducted as a function of pH, nor does it appear to strongly affect the Cd-binding groups as observed by FTIR. However, fluorescence microscopy indicates that Cd, although concentrated on cell walls, is also bound to some extent to EPS. Together, the results from this study suggest that the P. putida EPS can bind significant concentrations of Cd from solution, and that the nature and mass-normalized extent of the binding is similar to that of the cell wall. Therefore, the EPS-bearing systems do not exhibit enhanced mass-normalized removal of Cd from solution relative to the EPS-free systems. The presence of the EPS effectively increases the viability of cells exposed to aqueous Cd, likely due to sequestration of the Cd away from the cells due to Cd-EPS binding.