RT Journal Article SR Electronic(1) A1 Reimmann, Cornelia A1 Ginet, Nathalie A1 Michel, Laurent A1 Keel, Christoph A1 Michaux, Patrick A1 Krishnapillai, Viji A1 Zala, Marcello A1 Heurlier, Karin A1 Triandafillu, Karine A1 Harms, Hauke A1 Défago, Geneviève A1 Haas, DieterYR 2002 T1 Genetically programmed autoinducer destruction reduces virulence gene expression and swarming motility in Pseudomonas aeruginosa PAO1The GenBank accession number for the aiiA nucleotide sequence is AF397400. The GenBank accession numbers for the nucleotide sequences of the 16S rRNA genes of strains A23 and A24 are AF397398 and AF397399. JF Microbiology, VO 148 IS 4 SP 923 OP 932 DO https://doi.org/10.1099/00221287-148-4-923 PB Microbiology Society, SN 1465-2080, AB 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., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-148-4-923