Abstract
ABSTRACTThe 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. IMPORTANCE 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.
Highlights
The ecological and evolutionary forces that promote and maintain diversity in biofilms are not well understood
One of the most concerning examples involves biofilms associated with chronic lung infections of persons with cystic fibrosis (CF), in which distinct colony types that differ in traits such as antibiotic resistance, motility, quorum sensing, and adherence evolve [9,10,11,12,13], resulting in infections that are nearly impossible to eradicate [14,15,16]
Short-term experimental microbial evolution (EME) studies focusing on biofilm adaptation have been fruitful and have yielded phenotypes commonly seen during chronic lung infections such as mucoidy, small-colony variants (SCVs), loss of virulence factor production, and changes in cell surface virulence determinants [18,19,20]
Summary
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. 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. Clinical isolates of Pseudomonas aeruginosa commonly vary in motility and biofilm production [22] This diversity might represent selection to occupy distinct niches generated by other mutants or species, as has been shown in simple laboratory models [23,24,25]. In studies with Burkholderia cenocepacia, similar, heritable colony phenotypes evolved in each replicate population that associated with distinct ecological strategies
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
