UC San Diego

The ability of microorganisms to exchange electrons directly with their environment has large implications for our knowledge of industrial as well as for environmental processes. For decades, it has been known that microbes can use electrodes as electron acceptors in microbial fuel cell settings. Recently, it has been shown that organisms are also capable to accept electrons directly from an electrode for fixation of carbon dioxide into multi-carbon molecules (Microbial Electrosynthesis). The origin of these industrially relevant processes probably lies in the ability of microorganisms to transfer electrons directly between each other. Such interactions between microorganisms play a major role in the functioning of global biogeochemical cycles. Hence, there is a great need to gain mechanistic insights into the various factors governing microbial extracellular electron transfer. In this thesis, a genome-scale systems biology approach is applied to characterize these three aspects of electromicrobiology (microbial fuel cell, microbial electrosysnthesis, and interspecies electron transfer). First, we apply next-generation sequencing (NGS) technologies to de novo assemble the complete genome sequence of an enhanced electricity producing variant of an organism in a microbial fuel cell. This was further extended to the characterization of regulatory networks governing electrogenic biofilm growth using multi-omic data sets. In the second part, a genome-scale characterization of the metabolic capabilities of two electrosynthetic bacteria is presented. Finally, we demonstrate how analysis of multi-omic data in the context of genome-scale models microbial consortia enables us to decipher the underlying mechanism and cellular requirements for direct electron transfer in microbial associations