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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/2010

Title: Quorum signal molecules as biosurfactants affecting swarming in Rhizobium etli
Authors: DANIELS, Ruth
Reynaert, S
Hoekstra, H
Verreth, C
Fauvart, M
Beullens, S
Heusdens, C
Vanderleyden, J
Vermant, J
Michiels, J
JANSSENS, J
BRAEKEN, K
LAMBRICHTS, Ivo
DE VOS, D
Issue Date: 2006
Publisher: NATL ACAD SCIENCES
Citation: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 103(40). p. 14965-14970
Abstract: Swarming motility is suggested to be a social phenomenon that enables groups of bacteria to coordinately and rapidly move atop solid surfaces. This multicellular behavior, during which the apparently organized bacterial populations are embedded in an extracellular slime layer, has previously been linked with biofilm formation and virulence. Many population density-controlled activities involve the activation of complex signaling pathways using small diffusible molecules, also known as autoinducers. In Gram-negative bacteria, quorum sensing (QS) is achieved primarily by means of N-acylhomoserine lactones (AHLs). Here, we report on a dual function of AHL molecules in controlling swarming behavior of Rhizobium etli, the bacterial symbiotic partner of the common bean plant. The major swarming regulator of R. etli is the cinIR QS system, which is specifically activated in swarming cells by its cognate AHL and other long-chain AHLs. This signaling role of long-chain AHLs is required for high-level expression of the cin and rai QS systems. Besides this signaling function, the long-chain AHLs also have a direct role in surface movement of swarmer cells as these molecules possess significant surface activity and induce liquid flows, known as Marangoni flows, as a result of gradients in surface tension at biologically relevant concentrations. These results point to an as-yet-undisclosed direct role of long-chain AHL molecules as biosurfactants.
Notes: Katholieke Univ Leuven, Dept Microbiol & Mol Syst, Ctr Microbial & Plant Genet, B-3001 Louvain, Belgium. Katholieke Univ Leuven, Dept Chem Engn, Appl Rheol & Polymer Proc Sect, B-3001 Heverlee, Belgium. Katholieke Univ Leuven, Dept Microbial & Mol Syst, Ctr Surface Chem & Catalysis, B-3001 Heverlee, Belgium. Hasselt Univ, Biomed Res Inst, B-3590 Diepenbeek, Belgium.Michiels, J, Katholieke Univ Leuven, Dept Microbiol & Mol Syst, Ctr Microbial & Plant Genet, Kasteelpk Arenberg 20, B-3001 Louvain, Belgium.jan.michiels@biw.kuleuven.be
URI: http://hdl.handle.net/1942/2010
DOI: 10.1073/pnas.0511037103
ISI #: 000241069300058
ISSN: 0027-8424
Category: A1
Type: Journal Contribution
Validation: ecoom, 2007
Appears in Collections: Research publications

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