title: Discovery of complex mixtures of novel long-chain quorum sensing signals in free-living and host-associated marine alphaproteobacteria.
abstract: More than 100 bacterial isolates from various marine habitats were screened for AHL production by using gfp reporter constructs based on the lasR system of Pseudomonas aeruginosa and the luxR system of Vibrio fischeri. Of the 67 Alphaproteobacteria tested, most of which belonged into the so-called Roseobacter clade, 39 induced fluorescence in either one or both sensor strains up to 103-fold compared to controls. Acylated homoserine lactones were identified by GC-MS analysis and shown to have chain lengths of C8, C10, C13-C16, and C18. One or two double bonds were often present, while a keto or hydroxyl group occurred only rarely in the side chain. Most strains produced several different AHLs. C18-en-HSL and C18-dien-HSL were produced by Dinoroseobacter shibae, an aerobic anoxygenic phototrophic bacterium isolated from dinoflagellates, and are among the longest AHLs found to date. Z7-C14-en-HSL, which has previously been detected in Rhodobacter sphaeroides, was produced by Roseovarius tolerans and Jannaschia helgolandensis. This signal molecule was synthesised and shown to induce a similar response to the culture supernatant in the respective sensor strain. The widespread occurrence of quorum-sensing compounds in marine Alphaproteobacteria, both free-living strains and those associated to eukaryotic algae, points to a great importance of this signalling mechanism for the adaptation of the organisms to their widely different ecological niches.
authors.affiliation: National Research Institute for Biotechnology (GBF), Division of Cell Biology, Group Microbial Communication, Mascheroder Weg 1, 38124 Braunschweig, Germany. iwd@gbf.de
authors.forename: Irene
authors.initials: I
authors.lastname: Wagner-Döbler
authors.forename: Verena
authors.initials: V
authors.lastname: Thiel
authors.forename: Leo
authors.initials: L
authors.lastname: Eberl
authors.forename: Martin
authors.initials: M
authors.lastname: Allgaier
authors.forename: Agnes
authors.initials: A
authors.lastname: Bodor
authors.forename: Sandra
authors.initials: S
authors.lastname: Meyer
authors.forename: Sabrina
authors.initials: S
authors.lastname: Ebner
authors.forename: Andreas
authors.initials: A
authors.lastname: Hennig
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Pukall
authors.forename: Stefan
authors.initials: S
authors.lastname: Schulz
mesh_terms: D020561:Alphaproteobacteria / Q000302:isolation & purification* / Q000502:physiology; D015374:Biosensing Techniques / Q000379:methods*; D002450:Cell Communication; D015964:Gene Expression Regulation, Bacterial; D007783:Lactones / Q000032:analysis*; D008386:Marine Biology; D015398:Signal Transduction
chemical_list: D007783:Lactones