title: Rapid evolution of culture-impaired bacteria during adaptation to biofilm growth.
abstract: Biofilm growth increases the fitness of bacteria in harsh conditions. However, bacteria from clinical and environmental biofilms can exhibit impaired growth in culture, even when the species involved are readily culturable and permissive conditions are used. Here, we show that culture-impaired variants of Pseudomonas aeruginosa arise rapidly and become abundant in laboratory biofilms. The culture-impaired phenotype is caused by mutations that alter the outer-membrane lipopolysaccharide structure. Within biofilms, the lipopolysaccharide mutations markedly increase bacterial fitness. However, outside the protected biofilm environment, the mutations sensitize the variants to killing by a self-produced antimicrobial agent. Thus, a biofilm-mediated adaptation produces a stark fitness trade-off that compromises bacterial survival in culture. Trade-offs like this could limit the ability of bacteria to transition between biofilm growth and the free-living state and produce bacterial populations that escape detection by culture-based sampling.
authors.affiliation: Departments of Medicine and Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA. Electronic address: pntrmn@mit.edu.
authors.forename: Jon
authors.initials: J
authors.lastname: Penterman
authors.affiliation: Department of Medicine, McGill University, Montreal, QC H3G 1A4, Canada.
authors.forename: Dao
authors.initials: D
authors.lastname: Nguyen
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
authors.forename: Erin
authors.initials: E
authors.lastname: Anderson
authors.affiliation: Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Staudinger
authors.affiliation: Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA.
authors.forename: Everett P
authors.initials: EP
authors.lastname: Greenberg
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Lam
authors.affiliation: Departments of Medicine and Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA.
authors.forename: Pradeep K
authors.initials: PK
authors.lastname: Singh
mesh_terms: D000222:Adaptation, Physiological; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics; D018441:Biofilms / Q000254:growth & development*; D019143:Evolution, Molecular; D056084:Genetic Fitness; D008070:Lipopolysaccharides / Q000737:chemistry; D009154:Mutation; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000502:physiology
chemical_list: D001425:Bacterial Outer Membrane Proteins; D008070:Lipopolysaccharides