Investigation and Engineering of Electroactive Microbial Consortia
Complexity in microbial communities is essential for their survival and performance in environments ranging from the human gut to deep sea vents. In many cases, mixed communities have inherent spatial organization. However, the dearth of methods available to study these organisms with spatial control has made the investigation of interspecies interactions challenging. Of particular interest are microbial communities capable of extracellular electron transfer (EET), as EET enables such communities to perform activities relevant to the army, including bioremediation, wastewater treatment, and generation of electricity in non-ideal environments. We are studying the fundamental electron transfer properties of EET-competent microbiomes to better understand them and engineer them for energy applications. We are focusing on soil microbiomes to study fundamental ET processes, and we are initially engineering EET in a co-culture of Shewanella oneidensis and Geobacter sulfurreducens. These complementary strategies will enable us to understand fundamental principles of these systems and apply those principles to engineer the co-cultures more effectively.
Nanostructuring CO2 Reduction Catalysts using DNA
Carbon dioxide (CO2) is a common by-product of industrial processes, making it a promising renewable feedstock for value-added chemical production. Though many strategies exist for the conversion of CO2, electrocatalytic CO2 reduction (ECR) is one of the most prevalent. Heterogeneous ECR methods are especially common but can hinder catalyst-substrate interactions. Creative solutions have been employed to improve catalysis in these systems by engineering the immobilization of small-molecule catalysts on electrodes. However, many of these techniques focus on maximizing the catalyst loading on the surface with little concern for the precision of placement, which can lead to highly variable local environments and decreased efficiencies. To improve the efficiency and stability of heterogeneous ECR systems and elucidate structure-function relationships, we are developing a general method to precisely place molecular catalysts on electrodes using self-assembled nanomaterials constructed with deoxyribonucleic acid (DNA). We are evaluating the impact of two- and three-dimensional spacing on catalytic efficiency for two molecular ECR catalysts. To our knowledge, these studies represent the first example of a systematic evaluation of the influence of immobilization parameters on ECR. Based on our findings, we anticipate applying this nanostructuring method to additional classes of catalysts in the future.