Physical and Life Science Directorate, Lawrence Livermore National Laboratory , Livermore, California 94550, United States.
Univiersty of Washington , Earth and Space Sciences, Seattle, Washington 98195, United States.
Environ Sci Technol. 2017 Nov 21;51(22):13471-13480. doi: 10.1021/acs.est.7b02414. Epub 2017 Nov 2.
The use of biomass for adsorption of rare earth elements (REEs) has been the subject of many recent investigations. However, REE adsorption by bioengineered systems has been scarcely documented, and rarely tested with complex natural feedstocks. Herein, we engineered E. coli cells for enhanced cell surface-mediated extraction of REEs by functionalizing the OmpA protein with 16 copies of a lanthanide binding tag (LBT). Through biosorption experiments conducted with leachates from metal-mine tailings and rare earth deposits, we show that functionalization of the cell surface with LBT yielded several notable advantages over the nonengineered control. First, the efficiency of REE adsorption from all leachates was enhanced as indicated by a 2-10-fold increase in distribution coefficients for individual REEs. Second, the relative affinity of the cell surface for REEs was increased over all non-REEs except Cu. Third, LBT-display systematically enhanced the affinity of the cell surface for REEs as a function of decreasing atomic radius, providing a means to separate high value heavy REEs from more common light REEs. Together, our results demonstrate that REE biosorption of high efficiency and selectivity from low-grade feedstocks can be achieved by engineering the native bacterial surface.
生物量用于吸附稀土元素（REEs）一直是许多近期研究的主题。然而，生物工程系统对 REE 的吸附作用鲜有记录，且很少用复杂的天然原料进行测试。在此，我们通过在 OmpA 蛋白上功能化 16 个镧系元素结合标签（LBT），来构建可增强细胞表面介导的 REE 提取的大肠杆菌细胞，以用于 REE 的吸附。通过用从金属矿尾矿和稀土矿床浸出液进行的生物吸附实验，我们表明，与非工程对照相比，用 LBT 对细胞表面进行功能化具有多个显著优势。首先，指示个别 REE 分配系数增加 2-10 倍，所有浸出液中 REE 的吸附效率均得到增强。其次，除 Cu 以外，细胞表面对 REE 的相对亲和力均高于所有非 REE。第三，LBT 显示系统地增强了细胞表面对 REE 的亲和力，这是作为原子半径减小的函数，为从更常见的轻 REE 中分离高价值重 REE 提供了一种方法。总之，我们的结果表明，可以通过工程化天然细菌表面，从低品位原料中实现高效和选择性的 REE 生物吸附。
