title: Evolution of Ecological Diversity in Biofilms of Pseudomonas aeruginosa by Altered Cyclic Diguanylate Signaling.
abstract: The ecological and evolutionary forces that promote and maintain diversity in biofilms are not well understood. To quantify these forces, three Pseudomonas aeruginosa populations were experimentally evolved from strain PA14 in a daily cycle of attachment, assembly, and dispersal for 600 generations. Each biofilm population evolved diverse colony morphologies and mutator genotypes defective in DNA mismatch repair. This diversity enhanced population fitness and biofilm output, owing partly to rare, early colonizing mutants that enhanced attachment of others. Evolved mutants exhibited various levels of the intracellular signal cyclic-di-GMP, which associated with their timing of adherence. Manipulating cyclic-di-GMP levels within individual mutants revealed a network of interactions in the population that depended on various attachment strategies related to this signal. Diversification in biofilms may therefore arise and be reinforced by initial colonists that enable community assembly.
  
  
  
  How biofilm diversity assembles, evolves, and contributes to community function is largely unknown. This presents a major challenge for understanding evolution during chronic infections and during the growth of all surface-associated microbes. We used experimental evolution to probe these dynamics and found that diversity, partly related to altered cyclic-di-GMP levels, arose and persisted due to the emergence of ecological interdependencies related to attachment patterns. Clonal isolates failed to capture population attributes, which points to the need to account for diversity in infections. More broadly, this study offers an experimental framework for linking phenotypic variation to distinct ecological strategies in biofilms and for studying eco-evolutionary interactions.
authors.affiliation: Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire, USA.
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Flynn
authors.affiliation: Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire, USA.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Dowell
authors.affiliation: Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire, USA.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Johnson
authors.affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Koestler
authors.affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Waters
authors.affiliation: Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire, USA Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA vaughn.cooper@pitt.edu.
authors.forename: Vaughn S
authors.identifier: 0000-0001-7726-0765
authors.initials: VS
authors.lastname: Cooper
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001431:Bacteriological Techniques; D018441:Biofilms / Q000254:growth & development*; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism; D019020:Directed Molecular Evolution; D017753:Ecosystem; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D009154:Mutation; D011550:Pseudomonas aeruginosa / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; C062025:bis(3',5')-cyclic diguanylic acid; D006152:Cyclic GMP