Campylobacter jejuni is the primary food borne bacterial pathogen in the developed world. The most important reservoir for C. jejuni is the gut of chickens, which are colonized commensally and efficiently by this organism. Predominantly the mucus filled crypts of the lower gastrointestinal tract are found to be colonized by C. jejuni, and the bacteria are expected to be attracted to this particular environment by chemotaxis. In order to explore the role of chemotaxis in C. jejuni colonization we are construction deletion mutants in the putative chemoreceptors of the sequenced strain NCTC11168. These mutants will be analyzed for their chemotatic capacity in order to investigate the chemoreceptor function and to identify matching chemoeffectors. Furthermore, selected mutants will be investigated for their ability to colonize chickens with focus on establishment, level, and persistence. Special emphasis will be held at characterizing the colonization of mucus layers.