Collaborative Research: Elucidating the roles of biogenic exudates in the cycling and uptake of rare earth elements

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Bacteria catalyze numerous processes that are critical for the flow of elements at local to global scales. In many cases, these processes are fueled by enzymes that require specific metal ions to function. In the last decade, lanthanum and other rare earth elements (REYs), which have long been thought to lack a role in biology, have been identified as cofactors for enzymes used by diverse bacteria. This exciting discovery further expands the periodic table of life and raises many questions about the biogeochemistry of REYs. A central tenant of the project is that, because REYs are not abundant in most environments, bacteria require specific strategies to acquire these elements from their environments. This project will identify and characterize molecules associated with bacterial uptake of REYs. Because REYs are strategic materials that are difficult to purify from ores and waste products, the results are not only important for understanding biological process but also may have implications for economic competitiveness and national security. There is a growing recognition that the microbial uptake of essential trace metals is mediated by biogenic chelating agents. The recent discovery that REYs are required for PQQ Type I alcohol-oxidizing enzymes in methylotrophic and other diverse bacteria coupled with the natural presence of REYs in non-biologically available chemical forms lead to the hypothesis that structurally distinct, but as-yet unidentified, biogenic chelating agents (lanthanophores) facilitate the solubilization and uptake of REYs from soils. This project combines microbiology with coordination, soil, and analytical chemical approaches to identify and characterize lanthanophores, bacteriogenic ligands that promote solubilization and binding of REYs from soils and other matrices. The result of this project have the potential to transform our view of the importance of REYs in biological systems and their impact on nutrient cycling and revise current thinking towards nutrient uptake and the relationships between microorganisms and mineral matrices.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.