Bacterial nanowires: electrically conductive filaments and their implications for energy transformation and distribution in natural and engineered systems

Bacteria, ranging from oxygenic photosynthetic cyanobacteria to heterotrophic sulfate reducing bacteria, produce electrically-conductive appendages referred to as bacterial nanowires. Dissimilatory metal reducing bacteria, including Shewanella oneidensis and Geobacter sulfurreducens, produce electrically conductive nanowires in direct response to electron acceptor limitation and facilitate electron transfer to solid phase iron oxides. Nanowires produced by S. oneidensis strain MR-1, which served as our primary model organism, are functionalized by decaheme cytochromes MtrC and OmcA that are distributed along the length of the nanowires. Mutants deficient in MtrC and OmcA produce nanowires that were poorly conductive. These mutants also differ from wild type cells in their ability to reduce solid phase iron oxides, to produce electrical current in a mediator less microbial fuel cell, and to form complex biofilms at air liquid interfaces. Although currently less completely characterized, conductive nanowires produced by other organisms reveal a strategy of energy/electron distribution that is conserved across a broad metabolic spectrum. This presentation will target the implications of bacterial nanowire for energy distribution and communication in biofilms and other natural microbial communities, bioelectrical coupling of electron donors with poorly accessible electron acceptors, and applications for alternative energy (microbial fuel cells) and nanoelectronic technologies