Background
Rare earth elements (REEs), including scandium, yttrium and 15 lanthanides. They have very unique physical and chemical properties and are known as the ‘vitamins of industry’, with important applications in the manufacture of permanent magnet materials, electronic equipment, new energy vehicles, glass and ceramics, magnetic resonance imaging and other fields.
Figure 1. 17 Rare Earth Elements in the Periodic Table of Elements
The global rare earth elements market size was USD 3.39 billion in 2023 and is expected to grow to USD 8.14 billion by 2032, at a CAGR of 10.2%. This growth is mainly driven by the growing demand for consumer durables such as tablets, laptops, and smartphones. In addition, stringent regulations on carbon emissions and growing environmental concerns are fuelling the development of new energy sources, which will further increase the use of rare earth elements.
Figure 2. Uses of the Rare Earth Elements.
Pollution from rare earth mining
However, where are the rare earth elements going to come from? The scarcity and non-renewability of rare earth elements in nature have led to an increasing focus on how to sustainably separate and recover rare earth elements from rare earth ores and mine waste liquids. Traditional smelting and separation and extraction processes for rare earth resources include pyrometallurgy, hydrometallurgy, etc. For example, after the rare earth ores are stripped of rare earth metals by adopting concentrated sulphuric acid roasting and water leaching processes, they are then separated and purified by chemical precipitation and solvent extraction. In fact, the use of these traditional processes to recover rare earth elements inevitably involves huge energy consumption problems, complex processes, and serious pollution and damage to the environment. Therefore, we need to seek gentler and more environmentally friendly processes for the efficient extraction and recovery of rare earth resources.
Figure 3. Mine wastewater pollution
Biomining for rare earth recovery
Fortunately, nature has provided us with the answer. Microorganisms that interact with rare-earth minerals are naturally present in mineral deposits, and the development of synthetic biology has made it possible to re-engineer microorganisms for sustainable biomining applications. Biomining, which involves the leaching and extraction of rare earth metals through bioleaching, biosorption and bioaccumulation, is significantly more cost-effective than traditional physical and chemical mining techniques, is gentler, and meets the expectations of sustainable development.
Figure 4. Biomining
Some ligands and proteins have been found to bind lanthanide metals
efficiently, such as lanthanide-binding tags (LBTs) [1], lanthanide-modulating
proteins (Lanmodulin) [2], and so on. iGEM Calgary 2021,
iGEM HUST-China 2022,
and
iGEM Aachen 2023
have already achieved the recovery of lanthanides from
e-waste products or mine wastewater by using LBT or lanmodulin.
Recently, it has come to our attention that a new lanthanide-binding protein with ultra-high affinity, TFD, has been de novo designed by symmetric fusion design [3].TFD has a significantly higher affinity for lanthanide metals than the natural lanthanide-binding protein, lanmodulin, and is highly stable. This has stimulated great research interest for us! We introduced TFD into our project, thus opening up more possibilities for improving the efficiency of lanthanide biosorption recovery.
In addition, introducing such a de novo designed protein into iGEM would be of great significance, since the ultimate goal of synthetic biology is to develop completely new, ab initio biological systems for solving real-world problems.
Our project: CaptuREE
iGEM HiZJU-China 2024 is dedicated to developing an environmentally friendly sustainable biomining process for lanthanide rare earth elements. From this de novo designed lanthanide-binding protein TFD as a starting point, we have developed a complete rare earth element biomining process for the enrichment and recovery of lanthanide rare earth elements by integrating bioleaching and biosorption modules.
For more information about our project, please see
Design.
Figure 5. CapturREE: Schematic diagram of a sustainable biomining process for lanthanide rare earth elements
References
- [1] MacKenzie, C. Roger, et al. Bifunctional fusion proteins consisting of a single-chain antibody and an engineered lanthanide-binding protein. Immunotechnology. 1995, 1(2): 139-150.
- [2] Cotruvo Jr, Joseph A., et al. Lanmodulin: a highly selective lanthanide-binding protein from a lanthanide-utilizing bacterium. Journal of the American Chemical Society. 2018, 140(44): 15056-15061.
- [3] Caldwell, Shane J., et al. Tight and specific lanthanide binding in a de novo TIM barrel with a large internal cavity designed by symmetric domain fusion. Proceedings of the National Academy of Sciences. 2020, 117(48): 30362-30369.