Biofilms are associated with hundreds of thousands of infections each year and greatly increase treatment costs and mortality. These adverse effects are caused not only by increased resistance of bacteria living in the biofilm matrix but likely also by adaptive evolution of mutants into different, recalcitrant forms. To study this evolutionary process in biofilms we devised a method enabling long-term selection of populations of the opportunistic pathogen Burkholderia cenocepacia that undergo a cycle of attachment, biofilm assembly, and dispersal. Selection repeatedly favored mutations in loci commonly mutated during chronic infections, suggesting that biofilm adaptation recapitulates aspects of evolution during infections. This proposal focuses on two genetic loci that coordinate the sensing of a secreted signal (BDSF) with internal regulation of a switch governing biofilm production (cyclic-di-GMP). Mutations in different protein domains led to different ecological strategies and together different mutants produced a more robust biofilm. The overarching goal of this project is to precisely define the selective advantages of mutants with different strategie of signaling, adhesion, and dispersal in diverse biofilm environments. To tackle this complex problem we have assembled a multidisciplinary team with expertise in molecular genetics and evolutionary biology, biochemistry and mass spectrometry, and biophysical structure-function analysis. Our objectives are to 1) quantify how mutants that vary in sensing BDSF and producing cyclic-di-GMP are adaptive in biofilm communities, 2) determine how BDSF mechanistically controls the activity of the primary locus under selection, and the effects of adaptive mutations on this process, and 3) to develop an ecological model of how these processes operate in mixed-mutant and mixed-species communities. We expect to learn how this system may be manipulated to induce dispersal from biofilms and increase their susceptibility, which could be broadly relevant for developing novel antimicrobials.

Public Health Relevance

We will identify the precise phenotypes under selection as Burkholderia evolve to form biofilms and adapt to colonize distinct niches, a process that yields more resilient and productive communities. This dynamic of evolutionary diversification commonly occurs within chronic infections and is associated with their exceptional disease burden. Experimental evolution allows us to identify the genetic and physiological basis of these adaptations, and using advanced biochemistry and structural biology we will define how these mutations ultimately enhance the fitness of biofilm colonists.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM110444-04
Application #
9258441
Study Section
Genetic Variation and Evolution Study Section (GVE)
Program Officer
Reddy, Michael K
Project Start
2015-01-01
Project End
2019-12-31
Budget Start
2017-01-01
Budget End
2017-12-31
Support Year
4
Fiscal Year
2017
Total Cost
$241,731
Indirect Cost
$19,835
Name
University of Pittsburgh
Department
Genetics
Type
Schools of Medicine
DUNS #
004514360
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Fernandez, Nicolas; Waters, Christopher M (2018) Analyzing Diguanylate Cyclase Activity In Vivo using a Heterologous Escherichia coli Host. Curr Protoc Microbiol :e74
Maiden, Michael M; Hunt, Alessandra M Agostinho; Zachos, Mitchell P et al. (2018) Triclosan Is an Aminoglycoside Adjuvant for Eradication of Pseudomonas aeruginosa Biofilms. Antimicrob Agents Chemother 62:
Severin, Geoffrey B; Ramliden, Miriam S; Hawver, Lisa A et al. (2018) Direct activation of a phospholipase by cyclic GMP-AMP in El Tor Vibrio cholerae. Proc Natl Acad Sci U S A 115:E6048-E6055
Fernandez, Nicolas L; Srivastava, Disha; Ngouajio, Amanda L et al. (2018) Cyclic di-GMP Positively Regulates DNA Repair in Vibrio cholerae. J Bacteriol 200:
Cooper, Vaughn S (2018) Experimental Evolution as a High-Throughput Screen for Genetic Adaptations. mSphere 3:
Silva, InĂªs N; Pessoa, Filipa D; Ramires, Marcelo J et al. (2018) The OmpR Regulator of Burkholderia multivorans Controls Mucoid-to-Nonmucoid Transition and Other Cell Envelope Properties Associated with Persistence in the Cystic Fibrosis Lung. J Bacteriol 200:
Pursley, Benjamin R; Maiden, Michael M; Hsieh, Meng-Lun et al. (2018) Cyclic di-GMP Regulates TfoY in Vibrio cholerae To Control Motility by both Transcriptional and Posttranscriptional Mechanisms. J Bacteriol 200:
Bruger, Eric L; Waters, Christopher M (2018) Maximizing Growth Yield and Dispersal via Quorum Sensing Promotes Cooperation in Vibrio Bacteria. Appl Environ Microbiol 84:
Turner, Caroline B; Marshall, Christopher W; Cooper, Vaughn S (2018) Parallel genetic adaptation across environments differing in mode of growth or resource availability. Evol Lett 2:355-367
Connelly, B D; Bruger, E L; McKinley, P K et al. (2017) Resource abundance and the critical transition to cooperation. J Evol Biol 30:750-761

Showing the most recent 10 out of 21 publications