Phenotypic differentiation and seeding dispersal in non-mucoid and mucoid Pseudomonas aeruginosa biofilms.
There is growing evidence that Pseudomonas aeruginosa biofilms exhibit a multicellular developmental life cycle analogous to that of the myxobacteria. In non-mucoid PAO1 biofilms cultured in glass flow cells the phenotypic differentiation of microcolonies into a motile phenotype in the interior of the microcolony and a non-motile surrounding 'wall phenotype' are described. After differentiation the interior cells coordinately evacuated the microcolony from local break out points and spread over the wall of the flow cell, suggesting that the specialized microcolonies were analogous to crude fruiting bodies. A microcolony diameter of approximately 80 microm was required for differentiation, suggesting that regulation was related to cell density and mass transfer conditions. This phenomenon was termed 'seeding dispersal' to differentiate it from 'erosion' which is the passive removal of single cells by fluid shear. Using the flow cell culturing method, in which reproducible seeding phenotype in PAO1 wild-type was demonstrated, the effects of quorum sensing (QS) and rhamnolipid production (factors previously identified as important in determining biofilm structure) on seeding dispersal using knockout mutants isogenic with PAO1 was investigated. Rhamnolipid (rhlA) was not required for seeding dispersal but las/rhl QS (PAO1-JP2) was, in our system. To assess the clinical relevance of these data, mucoid P. aeruginosa cystic fibrosis isolate FRD1 was also investigated and was seeding-dispersal-negative.
Purevdorj-Gage
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Center for Biofilm Engineering, 366 EPS Building - PO Box 173980, Montana State University-Bozeman, MT 59717, USA.
Costerton
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Center for Biofilm Engineering, 366 EPS Building - PO Box 173980, Montana State University-Bozeman, MT 59717, USA.
Stoodley
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Center for Genomic Sciences, Allegheny-Singer Research Institute, Pittsburgh, USA.|Center for Biofilm Engineering, 366 EPS Building - PO Box 173980, Montana State University-Bozeman, MT 59717, USA.
D018441:Biofilms / Q000254:growth & development*; D003470:Culture Media; D004548:Elasticity; D015964:Gene Expression Regulation, Bacterial; D006017:Glycolipids / Q000378:metabolism; D006801:Humans; D009068:Movement; D009154:Mutation; D010641:Phenotype; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D015398:Signal Transduction; D013501:Surface-Active Agents / Q000378:metabolism; D014783:Viscosity
D003470:Culture Media; D006017:Glycolipids; D013501:Surface-Active Agents; C418382:rhamnolipid