Conductive microbial consortia for accelerating interspecies extracellular metabolism and living electronics

About This Grant

Every living cell needs to eliminate excess electrons when metabolism converts nutrients into energy. That, in essence, is why we breathe oxygen, which acts as a terminal electron acceptor. However, to survive in harsh environments lacking such soluble, ingestible molecules, the common soil bacterium Geobacter has evolved hair-like filaments that function as “nanowires,” to export electrons to extracellular acceptors and syntrophic partner species in a process called Direct Interspecies Electron Transfer (DIET). Exactly how microbes perform DIET has remained a mystery. Understanding DIET could help mitigate environmental changes, pollution, and the energy crisis, as DIET-performing microbes drive various globally-important phenomena, such as carbon & mineral cycling, bioremediation, corrosion, and chemical or biofuel production. Nanowires and wired cells could also be used for sustainable and living electronics applications. In addition, this highly interdisciplinary project will train students from diverse research backgrounds to harness the power of electric microbes in providing environmental solutions. It will prepare the next generation of interdisciplinary scientists at the interface of biology, physics, chemistry, data science, and engineering. The PI will leverage local infrastructure to encourage the active participation of students from diverse educational backgrounds through research programs, seminars, bootcamps, local community and outreach events for students. To understand how individual species switch to syntrophic growth to build microbial communities that sustain environmental changes, this project proposes to construct a synthetic community of Geobacter metallireducens (Gm) and Geobacter sulfurreducens (Gs) that employs DIET via nanowires. These nanowires were thought to be pili proteins. However, the team of this proposal’s PI has found that Gs pili filaments remain intracellular, exhibit low electron conductivity, and display an atomic structure inconsistent with that of nanowires. Instead, they are required for the secretion of cytochrome filaments, which function as nanowires. Using novel approaches to visualize and quantify DIET in synthetic Gm-Gs communities connected via “nanowires”, the PI’s team will determine the molecular components and energy pathways responsible for the formation, maintenance, and function of these communities. In particular, this project’s goals are: (1) Identify the role of nanowires and DIET in community formation, maintenance, and function. (2) Determine the role of microbial environment in community formation, maintenance, and function by measuring its effect on nanowire conductivity and DIET. (3) Use multi-omics to quantify community response to environments to predict ecosystem behavior. (4) Examine the role of DIET beyond the model system with other environmentally important species. and (5) Assemble electronically conductive consortia for living and sustainable electronics. Fundamental insights gained from these studies in the DIET in synthetic model communities can be applied to natural communities. These insights will yield new strategies for maintaining and manipulating microbial communities that can survive in harsh environments lacking nutrients and energy, while also sustaining high fluid flow and significant temperature, pH, and pressure fluctuations. This essential knowledge will enable system and synthetic biology approaches to leverage omics and modeling approaches to understand the role of environmentally relevant microbial communities in biogeochemical cycles and the rhizosphere. This project is supported by the Systems and Synthetic Biology cluster within the Division of Molecular and Cellular Biosciences. 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.