CAREER: Elucidating the Interaction(s) Between Bacteria and Archaea in a Biocathode

San Diego State University Foundation, San Diego CA

Investigators

Abstract

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Some microbes can grow on electrodes. Electrogens are bacteria that can digest organic matter and generate electrons along with carbon dioxide. If the electrons can be shipped outside the cell, the bacteria are referred to as exoelectrogens. These bacteria can power electrical devices. They also supply electrons that drive important reactions to nearby organisms. This objective of this project is to understand how a known exoelectrogen interacts with a microbe that can convert carbon dioxide to methane, referred to as a methanogen. Communities of these two types of organisms can swap electrons and carbon-containing molecules back and forth. Understanding how this occurs can help us understand the details of the global carbon cycle. It could also lead to a carbon-neutral electric energy system. Training K-12 teachers from Hispanic-serving schools to conduct research and to incorporate engineering principles into lessons are other major objectives. This outreach will also engage K-12 students in STEM-focused mentorship activities with university students. Exoelectrogens influence the electron flow, carbon flow, and biomass formation in a methanogenic biocathode. M. maripaludis and S. oneidensis are the model methanogen and exoeletrogen used in the project. Carbon and electron transfer pathways will be mapped for single-microbe biocathodes and for a dual-population biocathode. CRISPR Cas9 mediated genome editing interrogate how electrons are passed from S. oneidensis to M. maripaludis, and where donated electrons enter the methanogenesis pathway. Carbon transport pathways will be elucidated using 13C labeling of carbon dioxide, formate, and lactate in various single- and dual-population biocathode configurations, followed by NMR spectroscopy of biomass, and kinetic modeling. Fluorescence microscopy, scanning electron microscopy, and transcriptomics analyses will be used to compare cell spatial orientation and biofilm-related gene expression in the single- and dual-population cathode biofilms. Project results will lead to a better understanding of biocathode bacteria-archaea interactions. This will ultimately support improved design and scaling up of bioelectrochemical systems for energy recovery and wastewater treatment. 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.