title: Interspecies signalling via the Stenotrophomonas maltophilia diffusible signal factor influences biofilm formation and polymyxin tolerance in Pseudomonas aeruginosa.
abstract: Interspecies signalling through the action of diffusible signal molecules can influence the behaviour of organisms growing in polymicrobial communities. Stenotrophomonas maltophilia and Pseudomonas aeruginosa occur ubiquitously in the environment and can be found together in diverse niches including the rhizosphere of plants and the cystic fibrosis lung. In mixed species biofilms, S. maltophilia substantially influenced the architecture of P. aeruginosa structures, which developed as extended filaments. This effect depended upon the synthesis of the diffusible signal factor (DSF) by S. maltophilia and could be mimicked by the addition of synthetic DSF. This response of P. aeruginosa to DSF required PA1396, a sensor kinase with an input domain of related amino acid sequence to the sensory input domain of RpfC, which is responsible for DSF perception in xanthomonads. Mutation of PA1396 or addition of DSF to P. aeruginosa led to increased levels of a number of proteins with roles in bacterial stress tolerance, including those implicated in resistance to cationic antimicrobial peptides. This effect was associated with increased tolerance to polymyxins. Homologues of PA1396 occur in a number of phytopathogenic and plant-associated pseudomonads, suggesting that modulation of bacterial behaviour through DSF-mediated interspecies signalling with xanthomonads is a phenomenon that occurs widely.
authors.affiliation: BIOMERIT Research Centre, Department of Microbiology, BioSciences Institute, National University of Ireland, Cork, Ireland.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Ryan
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Fouhy
authors.forename: Belen Fernandez
authors.initials: BF
authors.lastname: Garcia
authors.forename: Steven A
authors.initials: SA
authors.lastname: Watt
authors.forename: Karsten
authors.initials: K
authors.lastname: Niehaus
authors.forename: Liang
authors.initials: L
authors.lastname: Yang
authors.forename: Tim
authors.initials: T
authors.lastname: Tolker-Nielsen
authors.forename: J Maxwell
authors.initials: JM
authors.lastname: Dow
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D018441:Biofilms / Q000254:growth & development*; D024881:Drug Resistance, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D011113:Polymyxins / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D020615:Stenotrophomonas maltophilia / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D011113:Polymyxins