The main thrust of this multi-disciplinary BE (IDEA) project is to develop and apply novel scanning probe microscopic (SPM) techniques for imaging chemical and biochemical processes at microbe-mineral interfaces. The ability to obtain chemical, topographical and ultimately optical information simultaneously at microbe-mineral interfaces has limited investigation of complex biological systems in previous research. Our project fosters interactions between experts in the fields of chemistry, biochemistry, geochemistry, microbiology, fluids and mass transport, microfabrication and spectroscopy. For the investigation of complex chemical and physical processes at microbe-mineral interfaces, correlation of in-situ obtained chemical, topographical and optical information is necessary, in order to understand microbial cell chemistry. Micro- and nanoelectrodes are integrated into atomic force microscopy (AFM) or scanning nearfield optical microscopy (SNOM) tips based on optimized microfabricated cantilevers. Besides mercury/gold amalgam electrodes for detecting Fe2+ production, nano-pH-electrodes will be integrated into scanning probe tips, mapping pH variations at the microbe-mineral interface. Such multifunctional SPM tips will provide simultaneous topographical, optical and (electro)chemical information correlated in space and time down to the nanoscale. Quantitative mathematical modeling and simulation of the electrochemical and physical processes taking place during the scanning process is essential for fundamental understanding and interpretation of obtained results. The developed multifunctional scanning nanoprobes will be used to determine the mechanism of reductive dissolution of Fe(III) minerals in the presence of FeRB and/or chemical reductants. Dissimilatory Fe(III) reduction is a relatively recent addition to the suite of anaerobic respiratory processes carried out by microorganisms and plays a significant role in global carbon cycling. Finally, this combined analytical technique can be extended to other environmental microbial processes involving minerals, such as the reductive dissolution of uranium, the precipitation of rhodochrosite and siderite, and the formation of manganese oxides. In addition, multifunctional scanning nanoprobes will be applicable to a wide variety of electrochemically active complex processes in a multitude of relevant fields, such as corrosion/biocorrosion, neurophysiology and cell signaling.
