Zoeken naar het 'Quorum Sensing' system van Cupriavidus metallidurans CH34 en de functie ervan op aarde en in de ruimte

Sometimes, the behaviour of micro-organisms in space changes in a negative way. They become more virulent. This is of great concern in space research. On earth bacterial virulence is often influenced by a process called 'Quorum Sensing', a bacterial communication system that is controlled by population density. Understanding how QS-systems work might provide important insights on the functioning of changes in bacterial behaviour. In this thesis the QS-system of Cupriavidus metallidurans CH34 is investigated. This is done in silico with bio-informatic tools and experimentally by comparing the wild type CH34 with a PhcA QS-mutant strain of C. metallidurans using laboratory techniques like, micro-array, macroscopic swim tests, bio-assay, growth speed monitoring and carbon source consumption. First of all, the remarkable resemblance of the QS-systems of C. metallidurans and Ralstonia solanacearum is demonstrated. In C. metallidurans two metabolic processes, rubisco and hydrogen oxidation are activated by its QS-system. Also motility is enhanced in the presence of a high PhcA concentration, the QS-control protein. We discovered that the transcription factor VsrD is down-regulated and, consequently, becomes part of the PhcA regulon. The carbon source, gluconate, consumption seems not affected by QS-signalling.