In the present dissertation 3 typs of bioelectrochemical systems were developed. The 1st one was a microbial fuel cell which was tested in a domestic sewage treatment plant. An electrical current was produced while organic carbon and N2-compounds were removed from the wastewater. The 2 other systems served for the characterization of electrotrophic microbes. In this context the use of an carbon cathode as the sole electron donor for a genetically modified R. sphaeroides strain was demonstrated.