title: Genetically programmed autoinducer destruction reduces virulence gene expression and swarming motility in Pseudomonas aeruginosa PAO1.
abstract: Virulence in the opportunistic human pathogen Pseudomonas aeruginosa is controlled by cell density via diffusible signalling molecules ('autoinducers') of the N-acylhomoserine lactone (AHL) type. Two Bacillus sp. isolates (A23 and A24) with AHL-degrading activity were identified among a large collection of rhizosphere bacteria. From isolate A24 a gene was cloned which was similar to the aiiA gene, encoding an AHL lactonase in another Bacillus strain. Expression of the aiiA homologue from isolate A24 in P. aeruginosa PAO1 reduced the amount of the quorum sensing signal N-oxododecanoyl-L-homoserine lactone and completely prevented the accumulation of the second AHL signal, N-butyryl-L-homoserine lactone. This strongly reduced AHL content correlated with a markedly decreased expression and production of several virulence factors and cytotoxic compounds such as elastase, rhamnolipids, hydrogen cyanide and pyocyanin, and strongly reduced swarming. However, no effect was observed on flagellar swimming or on twitching motility, and aiiA expression did not affect bacterial adhesion to a polyvinylchloride surface. In conclusion, introduction of an AHL degradation gene into P. aeruginosa could block cell-cell communication and exoproduct formation, but failed to interfere with surface colonization.
authors.affiliation: Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015 Lausanne, Switzerland1.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Reimmann
authors.affiliation: Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015 Lausanne, Switzerland1.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Ginet
authors.affiliation: Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015 Lausanne, Switzerland1.
authors.forename: Laurent
authors.initials: L
authors.lastname: Michel
authors.affiliation: Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015 Lausanne, Switzerland1.
authors.forename: Christoph
authors.initials: C
authors.lastname: Keel
authors.affiliation: Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015 Lausanne, Switzerland1.
authors.forename: Patrick
authors.initials: P
authors.lastname: Michaux
authors.affiliation: Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015 Lausanne, Switzerland1.
authors.forename: Viji
authors.initials: V
authors.lastname: Krishnapillai
authors.affiliation: Institut für Pflanzenwissenschaften/Phytopathologie, ETH Zürich, CH-8092 Zürich, Switzerland2.
authors.forename: Marcello
authors.initials: M
authors.lastname: Zala
authors.affiliation: Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015 Lausanne, Switzerland1.
authors.forename: Karin
authors.initials: K
authors.lastname: Heurlier
authors.affiliation: IATE-Pédologie, EPFL, CH 1015 Lausanne, Switzerland3.
authors.forename: Karine
authors.initials: K
authors.lastname: Triandafillu
authors.affiliation: IATE-Pédologie, EPFL, CH 1015 Lausanne, Switzerland3.
authors.forename: Hauke
authors.initials: H
authors.lastname: Harms
authors.affiliation: Institut für Pflanzenwissenschaften/Phytopathologie, ETH Zürich, CH-8092 Zürich, Switzerland2.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Défago
authors.affiliation: Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015 Lausanne, Switzerland1.
authors.forename: Dieter
authors.initials: D
authors.lastname: Haas
mesh_terms: D001407:Bacillus / Q000235:genetics / Q000502:physiology; D001483:Base Sequence; D017931:DNA Primers; D006801:Humans; D008969:Molecular Sequence Data; D009068:Movement; D010957:Plasmids; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology; D014774:Virulence / Q000235:genetics*
chemical_list: D017931:DNA Primers