tumefaciens (Zhang et al., 2002). In the case of the bacteroidete MDV3100 cost T. maritimum, the presence of a QQ enzyme for long AHLs may represent an exclusion mechanism to interfere with the QS systems of competitors (Dong
& Zhang, 2005). Evidence is beginning to accumulate indicating that QS and QS inhibition processes, including enzymatic degradation of the signal or QQ, are important in the marine environment. Besides the well-characterized phenomenon of the production of furanones by the red alga D. pulchra to avoid surface colonization by Gram-negative biofilm formers (Givskov et al., 1996), QS systems mediated by AHLs have been found in many species of marine pathogenic bacteria (Bruhn et al., 2005). AHLs also seem to play an important role in the eukaryotic–prokaryotic interactions in the marine environment, as demonstrated by the importance of the production of AHLs by marine biofilms for the surface selection and permanent attachment of zoospores of the green alga Ulva (Tait et al., 2005), for spore release of the red alga Acrochaetium sp. (Weinberger et al., 2007), and for some initial larval settlement behaviours in the polychaete Hydroides elegans (Huang et al., 2007). As most of the isolates involved in algal morphogenesis belong to the CFB group (Hanzawa et al., 1998; Matsuo et al., 2003), the discovery of the production
and degradation of AHLs by members of this group provides the possibility of new interactions Vincristine chemical structure 3-mercaptopyruvate sulfurtransferase between bacteria and eukaryotes in the marine environment. For the first time, the production of AHL-type QS signals and QQ activity has been demonstrated simultaneously in a pathogenic member of the CFB group. Because of the ecological significance of the Cytophaga–Flavobacterium cluster, especially in the marine environment, the discovery of AHL-mediated QS processes among
their members will advance our understanding of the microbial interactions in complex ecosystems. Moreover, cell-to-cell communication phenomena should be reconsidered in other habitats in which the Bacteroidetes play an important role, such as intestinal flora or dental plaque. As QS controls the expression of important virulence factors in many pathogenic bacteria, the disruption of QS mechanisms in T. maritimum and other fish pathogenic bacteria may represent a new strategy for the treatment of infections in aquaculture. This work was financed by a grant from Consellería de Innovación e Industria, Xunta de Galicia, Spain (PGIDIT06PXIB200045PR). M.R. is supported by an FPU fellowship from the Spanish Ministry of Science and Education. We would like to thank Noemi Ladra (University of Santiago) and Catherine Ortori (University of Nottingham) for LC-MS analysis. The sensor Chromobacterium violaceum VIR07 was kindly provided by Prof. T. Morohoshi. “
“Biofilm detachment is a physiologically regulated process that facilitates the release of cells to colonize new sites and cause infections.