A Role for Microbial Palladium Nanoparticles in Extracellular Electron Transfer

Abstract

Insights into extracellular electron transfer of microorganisms are important for the understanding of electron transport pathways in bioelectrochemical systems (e.g. biological fuel cells and microbial electrolysis cells), as well as for biogeochemical cycles, biocorrosion and bioremediation[1-7]. Two principal mechanisms for extracellular electron transfer have been proposed: i) electroactive metabolites/secretions serve as mediators in an indirect electron transfer process; ii) electrons transfer directly from the cells to the electrodes via either membrane cytochromes or electrically conductive pili – the latter process has been defined in a termed direct electron transfer (DET) and has recently been the subject of intense study[3–7]. It is well known that several microbes are capable of transforming a range of metal ions/minerals into nanoparticles that are bound into the cell membrane. However, little is understood about the role of such metallic nanoparticles in the physiological electron transfer processes, and important questions remain regarding the details of the mechanisms involved