Molecular sensors are a key technology in respect to the accomplishment of the objectives of the young investigator group PLANKTOSENS. Molecular sensors provide the possibility to survey microbial organisms without previous cultivation. Surveillance of microbes with a molecular sensor is based on the detection of taxa via a specific interaction between a molecular probe that is bound to the surface of a sensor chip with a complementary nucleic acid e.g. rRNA genes in the genome of the target taxon.