State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; College of Resources and Environment, Linyi University, Linyi 276000, China.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
Environ Pollut. 2018 Jun;237:39-49. doi: 10.1016/j.envpol.2018.01.075. Epub 2018 Feb 20.
The primary objective of this study was to identify the capacity and mechanism of extracellular polymeric substance (EPS) adsorption on soil colloids of Alfisol and Ultisol at different pH and ionic strengths. Two kinds of EPS were extracted from Bacillus subtilis and Pseudomonas fluorescens by centrifugation, and their adsorption on Ultisol and Alfisol was investigated using a batch adsorption experiment and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The average diameter of EPS from B. subtilis and P. fluorescens was 1825 and 1288 nm, respectively, and both the EPS were negatively charged. The zeta potentials of the two EPS became more negative with increasing solution pH from 3 to 8 and less negative with increasing ionic strength from 0 to 80 mM. The maximum adsorption capacity of EPS-C and EPS-N on Alfisol was higher than that on Ultisol, whereas the maximum adsorption capacity of EPS-P on Alfisol was lower than that on Ultisol. The adsorption of EPS-C, EPS-N, and EPS-P of both the EPS on Ultisol and Alfisol decreased with increasing solution pH from 3 to 8. Adsorption of EPS-C, EPS-N, and EPS-P of both the EPS on Alfisol significantly increased with increasing ionic strength from 0 to 10 mM, whereas it remained constant, slightly increased, or reduced, when the ionic strength was increased from 10 to 80 mM. The adsorption of EPS-C, EPS-N, and EPS-P on Ultisol slightly increased with increasing ionic strength from 0 to 80 mM. Saturation coverage determined by ATR-FTIR showed that adsorption of whole EPS on Ultisol was higher than that on Alfisol at pH 6 after 60 min. Thus, electrostatic force between EPS and soil colloids played an important role in EPS adsorption. Besides, proteins and phosphate groups in EPS also contributed to EPS adsorption on soil colloids.
本研究的主要目的是确定在不同 pH 值和离子强度下，土壤胶体对芽孢杆菌和荧光假单胞菌产生的胞外聚合物（EPS）的吸附容量和机制。通过离心从枯草芽孢杆菌和荧光假单胞菌中提取了两种 EPS，并通过批量吸附实验和衰减全反射傅里叶变换红外光谱（ATR-FTIR）研究了它们对土壤胶体的吸附。枯草芽孢杆菌和荧光假单胞菌 EPS 的平均直径分别为 1825nm 和 1288nm，且两种 EPS 均带负电荷。随着溶液 pH 值从 3 增加到 8，两种 EPS 的 ζ 电位变得更负，而随着离子强度从 0 增加到 80mM，ζ 电位变得更负。EPS-C 和 EPS-N 在 Alfisol 上的最大吸附量高于 Ultisol，而 EPS-P 在 Alfisol 上的最大吸附量低于 Ultisol。两种 EPS 的 EPS-C、EPS-N 和 EPS-P 在 Ultisol 和 Alfisol 上的吸附均随溶液 pH 值从 3 增加到 8 而降低。两种 EPS 的 EPS-C、EPS-N 和 EPS-P 在 Alfisol 上的吸附随离子强度从 0 增加到 10mM 显著增加，而当离子强度从 10 增加到 80mM 时，吸附保持不变、略有增加或减少。两种 EPS 的 EPS-C、EPS-N 和 EPS-P 在 Ultisol 上的吸附随离子强度从 0 增加到 80mM 略有增加。通过 ATR-FTIR 确定的饱和覆盖率表明，在 pH 值为 6 下，60min 后，EPS 对 Ultisol 的吸附量高于 Alfisol。因此，EPS 和土壤胶体之间的静电力在 EPS 吸附中起重要作用。此外，EPS 中的蛋白质和磷酸盐基团也有助于 EPS 在土壤胶体上的吸附。
