The aim of this project is to investigate fundamental aspects of the physical chemistry of bacterial cell / substrate interactions. Well-defined surfaces of both single crystals and multi-layered gold deposits on quartz elements will be used to resolve the interfacial electrochemistry by capacitance measurements. The use of single crystal electrodes is essential in order to avoid the uncertainties of classical electrode surfaces that have a surface rugosity of the same order of magnitude as the dimensions o f the bacteria investigated. This will ensure a high degree of control and reproducibility of the electrode material. The potential dependence of bacterial attachment and biofilm formation on these surfaces will be studied by microgravimetry, infrared reflectance spectroscopy and ac impedance spectroscopy.The results will be used to develop an interfacial model of the potential distribution and therefore to calculate the interfacial capacitance of the cell membrane-interstitial solution- metal surface. Es cherichia coli cells will be used to exploit the metabolic change during the aerobic / anaerobic transition in order to determine the influence of metabolism on interfacial electrochemistry. Feeding with nutrients of different energetic yield will also be used to produce differential metabolic states. In addition, specific bacterial attachment to gold surfaces will be directed by surface modification with thiols containing a recognition termination. Live and dead cells will be used in the bacterial recognition experiments.