title: Lipopeptide biosurfactant viscosin enhances dispersal of Pseudomonas fluorescens SBW25 biofilms.
abstract: Pseudomonads produce several lipopeptide biosurfactants that have antimicrobial properties but that also facilitate surface motility and influence biofilm formation. Detailed studies addressing the significance of lipopeptides for biofilm formation and architecture are rare. Hence, the present study sets out to determine the specific role of the lipopeptide viscosin in Pseudomonas fluorescens SBW25 biofilm formation, architecture and dispersal, and to relate viscA gene expression to viscosin production and effect. Initially, we compared biofilm formation of SBW25 and the viscosin-deficient mutant strain SBW25ΔviscA in static microtitre assays. These experiments demonstrated that viscosin had little influence on the amount of biofilm formed by SBW25 during the early stages of biofilm development. Later, however, SBW25 formed significantly less biofilm than SBW25ΔviscA. The indication that viscosin is involved in biofilm dispersal was confirmed by chemical complementation of the mutant biofilm. Furthermore, a fluorescent bioreporter showed that viscA expression was induced in biofilms 4 h prior to dispersal. Subsequent detailed studies of biofilms formed in flow cells for up to 5 days revealed that SBW25 and SBW25ΔviscA developed comparable biofilms dominated by well-defined, mushroom-shaped structures. Carbon starvation was required to obtain biofilm dispersal in this system. Dispersal of SBW25 biofilms was significantly greater than of SBW25ΔviscA biofilms after 3 h and, importantly, carbon starvation strongly induced viscA expression, in particular for cells that were apparently leaving the biofilm. Thus, the present study points to a role for viscosin-facilitated motility in dispersal of SBW25 biofilms.
authors.affiliation: 1​ Section for Microbial Ecology and Biotechnology, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Lise
authors.initials: L
authors.lastname: Bonnichsen
authors.affiliation: 1​ Section for Microbial Ecology and Biotechnology, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Nanna
authors.initials: N
authors.lastname: Bygvraa Svenningsen
authors.affiliation: 2​ Costerton Biofilm Center, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: Rybtke
authors.affiliation: 3​ Microbial Ecology Department, Netherlands Institute of Ecology, Wageningen, The Netherlands.
authors.forename: Irene
authors.initials: I
authors.lastname: de Bruijn
authors.affiliation: 3​ Microbial Ecology Department, Netherlands Institute of Ecology, Wageningen, The Netherlands.
authors.forename: Jos M
authors.initials: JM
authors.lastname: Raaijmakers
authors.affiliation: 2​ Costerton Biofilm Center, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Tim
authors.initials: T
authors.lastname: Tolker-Nielsen
authors.affiliation: 1​ Section for Microbial Ecology and Biotechnology, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Ole
authors.initials: O
authors.lastname: Nybroe
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018441:Biofilms; D055666:Lipopeptides / Q000378:metabolism*; D010453:Peptide Synthases / Q000235:genetics / Q000378:metabolism; D010456:Peptides, Cyclic / Q000378:metabolism*; D011551:Pseudomonas fluorescens / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D013501:Surface-Active Agents / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D055666:Lipopeptides; D010456:Peptides, Cyclic; D013501:Surface-Active Agents; C062796:viscosin; D010453:Peptide Synthases