Bacteria talk to each other – but since they don't have mouths and ears, they do not use sound. Instead, they use small chemical signals called autoinducers. The type and amount of autoinducer molecules sensed by a bacterial cell tells it exactly how many of its own kind are around (“quorum sensing”), if there are related species present, and, even if there are unknown bacteria in the neighborhood. These autoinducer signals control the development of traits whose effectiveness is strongly dependent on cell density, e.g. luminescence, virulence, production of antibiotics, or biofilm formation. Their expression, therefore, is coordinated for the whole population.
The research group "Microbial Communication" focuses on a signaling molecule, which is used by many diverse bacterial species as a universal communication signal, the so-called autoinducer-2 (AI-2). The goal is to unravel the function of AI-2 in Streptococcus mutans, the causative agent of tooth decay, or caries, and in Shewanella, an opportunistic pathogen. To discover inhibitors of quorum sensing, natural compounds from Myxobacteria are studied, a group of soil bacteria which form fruiting bodies and produce many interesting secondary metabolites.
To this end, the methods of two very different field of research are combined: functional genome analysis and microbial ecology. We have developed, for example, a whole genome microarray (genechip) for Streptococcus mutans, which is now used to analyze the effect of cell density and quorum sensing blockers on the total gene expression of this dental caries inducing microorganism.
Microbial communication opens up a novel route for the development of anti-infective therapeutics. By disturbing the signaling cascade, the bacteria are kept ignorant of their true density and so they do not become virulent or do not form biofilms. To be able to manipulate these mechanisms, however, it is necessary to understand them in depth, which is the aim of the group “Microbial Communication”.
