Bacterial Cell Surface Adsorption of Rare Earth Elements

Tuesday, 15 December 2015
Poster Hall (Moscone South)
Yongqin Jiao1, Dan Park1, David Reed2, Yoshiko Fujita3, Mimi Yung1, Andre Anderko4 and Ali Eslamimanesh4, (1)Lawrence Livermore National Laboratory, Livermore, CA, United States, (2)Idaho National Lab, Idaho falls, ID, United States, (3)Idaho National Laboratory, Idaho Falls, ID, United States, (4)OLI Systems, Inc., Cedar Knolls, NJ, United States
Rare earth elements (REE) play a critical role in many emerging clean energy technologies, including high-power magnets, wind turbines, solar panels, hybrid/electric vehicle batteries and lamp phosphors. In order to sustain demand for such technologies given current domestic REE shortages, there is a need to develop new approaches for ore processing/refining and recycling of REE-containing materials. To this end, we have developed a microbially-mediated bioadsorption strategy with application towards enrichment of REE from complex mixtures. Specifically, the bacterium Caulobacter crescentus was genetically engineered to display lanthanide binding tags (LBTs), short peptides that possess high affinity and specificity for rare earth elements, on its cell surface S-layer protein. Under optimal conditions, LBT-displayed cells adsorbed greater than 5-fold more REE than control cells lacking LBTs. Competition binding experiments with a selection of REEs demonstrated that our engineered cells could facilitate separation of light- from heavy- REE. Importantly, binding of REE onto our engineered strains was much more favorable compared to non-REE metals. Finally, REE bound to the cell surface could be stripped off using citrate, providing an effective and non-toxic REE recovery method. Together, this data highlights the potential of our approach for selective REE enrichment from REE containing mixtures.