National Collaborative Innovation Center for Nuclear Waste and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010, China; Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010, China; Mianyang Central Hospital, NHC Key Laboratory of Nuclear Technology Medical Transformation，Mianyang 621000, China.
National Collaborative Innovation Center for Nuclear Waste and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010, China; Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-sen University, Zhuhai 519082, China.
Ecotoxicol Environ Saf. 2022 Aug;241:113719. doi: 10.1016/j.ecoenv.2022.113719. Epub 2022 Jun 9.
The influence of extracellular polymeric substances (EPS) on the interaction between uranium [U(VI)] and Shewanella putrefaciens (S. putrefaciens), especially the U(VI) biomineralization process occurring on whole cells and cell components of S. putrefaciens was investigated in this study. The removal efficiency of U(VI) by S. putrefaciens was decreased by 22% after extraction of EPS. Proteins were identified as the main components of EPS by EEM analysis and were determined to play a major role in the biosorption of uranium. SEM-EDS results showed that U(VI) was distributed around the whole cell as 500-nanometer schistose structures, which consisted primarily of U and P. However, similar uranium lamellar crystal were wrapped only on the surface of EPS-free S. putrefaciens cells. FTIR and XPS analysis indicated that phosphorus- and nitrogen-containing groups played important roles in complexing U (VI). XRD and U L-edge EXAFS analyses demonstrated that the schistose structure consisted of hydrogen uranyl phosphate [H(UO)(PO)•8HO]. Our study provides new insight into the mechanisms of induced uranium crystallization by EPS and cell wall membranes of living bacterial cells under aerobic conditions.
本研究考察了胞外聚合物（EPS）对铀（U(VI)）与脱硫肠状菌（Shewanella putrefaciens，S. putrefaciens）相互作用的影响，特别是 EPS 存在时，S. putrefaciens 细胞及其组分上发生的 U(VI)生物矿化过程。通过 EPS 萃取，S. putrefaciens 对 U(VI)的去除效率降低了 22%。通过 EEM 分析确定蛋白质是 EPS 的主要成分，并确定其在铀的生物吸附中起主要作用。SEM-EDS 结果表明，U(VI)呈 500 纳米片状结构分布在整个细胞周围，主要由 U 和 P 组成。然而，类似的铀层状晶体仅包裹在无 EPS 的 S. putrefaciens 细胞表面。FTIR 和 XPS 分析表明，含磷和氮的基团在 U(VI)络合中起重要作用。XRD 和 U L-edge EXAFS 分析表明，片状结构由磷酸双氧铀[H(UO)(PO)•8HO]组成。我们的研究为有氧条件下 EPS 和活细菌细胞壁诱导铀结晶的机制提供了新的见解。
