On October 30, Professor Yunjun Yan’ team from the College of Life Sciences and Technology of Huazhong University of Science and Technology published a research paper entitled " Effectively auto-regulated adsorption and recovery of rare earth elements via an engineered E. coli" in Journal of Hazardous Materials.
Rare earth elements play a crucial role in industry and our everyday life. With their exceptional magnetic, optical and mechanical properties, they prove indispensable in multiple areas such as power, pharmaceuticals and national defense industry. However, the conventional mining processes are usually accompanied by production of REEs-rich industrial liquid wastes. Direct discharge of the REEs-rich liquid wastes not only leads to a significant waste of REEs resources, but also causes serious environmental pollution. Therefore, recovery of REEs from liquid wastes in an economic, wide-adaptive and environment-friendly manner is highly urgent.
Microbial adsorption of REEs is an environmentally-friendly and easy-to-operate method with low cost. However, the efficiency, controllability and facilitation of the recovery procedure for microbial REEs adsorption need to be further greatly improved. In this study, to regulate the REEs’ adsorption and recovery by sensing extraneous REEs, an engineered cascaded induction system, pmrCAB operon containing a lanthanide-binding tag (LBT) for sensing REEs, was incorporated into E. coli in conjunction with a silica-binding protein (Si-tag) and dLBT anchored onto the cell membrane. As a result, a ‘cell factory’ that integrates the functions of sensing, adsorbing and convenient recovering of REEs was successfully constructed. The adsorption capacity for Tb reached the highest reported value of 41.9 mg·g-1 dry cell weight. After adhering the engineered cells onto the silica column surface through overexpressed Si-tag, a high recovering efficiency (> 90%) of Tb desorption could be achieved. Our findings showed that the recovery of REEs with high efficiency, selectivity and controllability from aqueous solution can be well realized via specifically bio-engineered strains (Fig.1).
Fig.1 The technical route of this study
Prof. Yunjun Yan from College of Life Science & Technology is the corresponding author of this research paper, and Dr. Xiaoman Xie is the first author. This study was financially supported by the National Natural Science Foundation of China and the Fundamental Research Funds for HUST.
The paper link: https://doi.org/10.1016/j.jhazmat.2021.127642.
