Nitesh Kanojia

Investigation of the interface between electrochemically-active microorganisms and metals

The ability to interact electronically with conductive materials is a defining feature of electrochemically-active microorganisms. This process, known as extracellular electron transfer, results in a microbially-derived current and has been investigated primarily from the vantage point of maximising power output or product yield in bioelectrochemical devices. As such, the majority of studies have focused on the interaction between these microorganisms and relatively low-cost conductive materials, such as graphite and other carbon-based electrodes. Reflecting the natural conditions in which most of these microorganisms have evolved, the microbial interface with iron has received considerable attention. However, the interaction with other relevant metals including gold, uranium and copper has been comparatively understudied. This study aims to examine the interface between these metals and electrochemically-active microorganisms during colonisation. Model electrochemically-active microorganisms will be used, including S. oneidensis and G. sulfurreducens, in addition to microorganisms enriched from natural materials (Au grains) and contaminated sites (U Mary Kathleen deposit and Cu Mount Isa Mines) possessing the respective metal of interest. Electroanalytical techniques including voltammetry, chronoamperometry and electrochemical impedance spectroscopy will probe the microbe-metal interface and will be complemented by molecular biology techniques to refine current understanding of the microbial response to various metals. The findings will increase fundamental understanding of extracellular electron transfer and have the potential to identify novel modes of extracellular electron transfer useful in bioelectrochemical systems.