Award: OCE-1542506

All known life is electrical life. All living organisms use the movement of electrons within each cell to generate energy, build new biomolecules, and send signals. Typically, for energy generation, organisms will take electrons away from electron-rich compounds (such as sugars, as we humans do) and pass them through their biochemical apparatus to electron-poor compounds (such as oxygen). The movement of electrons through these pathways drives the re-generation of ATP (our energy currency) as well as the synthesis of biological "building bocks" to make new biomolecules (these are called reducing equivalents, and NAPH is an example of a reducing equivalent). Until recently, it was thought that all cells ?from single-cell microbes to the largest plants and animals- require these compounds to be brought into the cell. However, about 30 years ago scientists discovered that some bacteria are able to use solid compounds such as rust (iron oxides) located outside the cell as the electron acceptor. They do so by shuttling electrons from the inside of the cell to the outside of the cell, via biomolecules that deliver electrical charge to the solid compounds in the environment. In other words, these microbes "breathe" rust, and part of these microbes? energy production pathways evolved to be outside of the cell. This process, termed extracellular electron transfer (EET), transformed how we think about cellular life and in particular how microbes may impact global biogeochemical cycles that keep our biosphere healthy. As one example, EET enables microbes to chemically alter minerals, including toxic elements such as Uranium, for energy generation without bringing those substances into the cell. This has profound implications for the mobility of such toxins in both natural and human-built ecosystems. To date, however, we have studied the biochemistry, physiology and ecology of EET in just a few cultured microbes in natural and human-made habitats. By applying a multi-faceted and interdisciplinary approach, our team will conduct the first wide-ranging assessment of the diversity of EET across all three domains of life. Specifically, the overarching goal of this proposal is to comprehensively assess and relate the phylogenetic diversity, genetic/genomic diversity, and functional diversity of microorganisms engaged in EET across all three domains of life. By virtue of our experimental design and project plan, this project will provide, for the first time, experiments that linking microbial identity (phylogenetic analyses) with their genomic capacity (metagenomics) and their metabolic/EET rates (transcriptomics, genetics, and metabolic rate measurements). While the value of each of the proposed efforts is significant, the coordination of these activities enables true integration of these findings and will yield the first comprehensive knowledge base for EET that can be used to identify new organisms that are capable of EET across all domains of life. Equally important, this research has caught the attention of companies across a diversity of sectors. Companies engaged in biofuel generation, soil remediation, wastewater treatment, and synthetic biology have used our research as a basis for further research, and potenitally to advance their product lines. In addition to the technical objectives, this project promoted the progress of science and support education and diversity. We broadened public understanding about microbial life through developing interactive museum exhibits that presents microbial EET to the public. We contributed to the Encyclopedia of Life to broaden the representation of microbes in their databases and school curricula. We developed a cross-university STEM program that uses "microbial fuel cells" to teach students about physics, chemistry, and biology through EET experiments. Further, our project strengthened industry and academic pipelines through educational curricula that engaged middle school and college-level students in EET research, and a pedagogical training and lab exchange program that afforded our students and postdocs an opportunity to conduct interdisciplinary research. Last Modified: 05/15/2021 Submitted by: Peter Girguis