@PhdThesis{diss_mods_00017855,
  author = 	{Pietschke, Cleo I.},
  title = 	{Inter-kingdom communication: quorum sensing and quorum quenching in the metaorganism Hydra},
  year = 	{2015},
  publisher = 	{Christian-Albrechts-Universit{\"a}t zu Kiel},
  address = 	{Kiel},
  keywords = 	{Hydra; metaorganism; quorum sensing; quorum quenching; host-microbe interaction; Curvibacter; Wirt-Bakterien-Interaktion},
  abstract = 	{Every metaorganism consisting of a host and its associated microbes needs to maintain its homeostasis. Bacteria are controlling their behavior by their communication system, called quorum sensing (QS). As a host is interested in suppressing processes as virulence, the interference with a QS system (quorum quenching, QQ) could be an instrument to regulate the behavior of its bacteria.
In this thesis, it could be proven that bacteria colonizing Hydra vulgaris (AEP) are producing N-acyl-homoserine-lactones, a class of QS signaling molecules. By analyzing the QS system of Curvibacter sp., the main colonizer of Hydra vulgaris (AEP), it could be shown that it can detect 3-hydroxy-HSLs (3OH-HSLs) as well as 3-oxo-HSLs (3O-HSLs) and produces 3OHC12. Furthermore, a new host mechanism could be identified, which enables Hydra to modify 3O-HSLs via an oxidoreductase activity to the 3OH-HSL counterpart. Consequently, Hydra's QQ activity promotes Curvibacter's 3OH-HSL regulated processes.
Transcriptional expression data revealed that Curvibacter sp. possesses a differential response to 3OHC12 and 3OC12. Thereby, genes involved in flagella biosynthesis were induced by 3OC12 and inhibited by 3OHC12. The AHLs have also different impacts on the metaorganism assembly. While 3OHC12 promotes, 3OC12 inhibits colonization of host tissue by Curvibacter sp., most likely by a flagellin activated innate immune response.
These findings indicate that 3O-HSLs induce the production of flagella in Curvibacter sp., which cause a response in Hydra, resulting in a decreased bacterial community within the metaorganism Hydra. These insights show for the first time, that a host is manipulating QS signals and thereby maintain symbiotic function of its bacteria, which contribute to the homeostasis of the metaorganism.},
  url = 	{https://macau.uni-kiel.de/receive/diss_mods_00017855},
  file = 	{:https://macau.uni-kiel.de/servlets/MCRFileNodeServlet/dissertation_derivate_00006345/Diss_Cleo%20Pietschke_edit.pdf:PDF},
  language = 	{en}
}