Poster: Plant Pathogen/Symbiont Interactions
Abs #
691: Pseudomonas aeruginosa biofilm: a protection against plant root-derived antimicrobials
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Presenter: |
Vivanco, Jorge , jvivanco@lamar.colostate.edu | Authors | Vivanco, Jorge (A) Walker, Travis (A) Bais, Harsh (A) Déziel, Eric (B) Schweizer, Herbert P (C) Rahme, Laurence G (B) Fall, Ray (D) | | Affiliations: |
(A): Department of Horticulture and Landscape Architecture, and Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO 8
(B): Department of Surgery, Harvard Medical School, Massachusetts General Hospital and Boston Shriners Institute, 50 Blossom Street, Boston, MA 0
(C): Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 8
(D): Department of Chemistry and Biochemistry, and Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder,
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Pseudomonas aeruginosa is an opportunistic human pathogen capable of forming an effective antibiotic-resistant biofilm contributing to its persistent and lethal infectious behavior despite aggressive antibiotic treatment. Here we report that pathogenic P. aeruginosa strains PA14 and PAO1 are capable of infecting the roots of Arabidopsis thaliana and Ocimum basilicum (sweet basil) both in vitro and in the soil, and cause plant mortality seven days post-inoculation. Prior to plant mortality, it was found that PA14 and PAO1 colonize the roots of A. thaliana and O. basilicum and form a biofilm. Upon P. aeruginosa infection, O. basilicum roots secrete rosmarinic acid (RA), a multifunctional caffeic acid ester that exhibited antibacterial activity against planktonic cells of both strains with a minimum inhibitory concentrations (MIC) of 3 µg/ml. However, MIC levels of RA did not disrupt or prevent the development of preformed biofilms. Studies with quorum-sensing mutants PAO210 (ÄrhlI), PAO214 (ÄlasI), and PAO216 (ÄlasI ÄrhlI) revealed that all strains remained pathogenic to A. thaliana, while only one, PAO214, was pathogenic to O. basilicum. PAO214 biofilm and cell counts on root surfaces appeared comparable to biofilms formed by wild-type strains. Our results collectively suggest that upon root colonization, P. aeruginosa forms a biofilm to protect itself against root-secreted antibiotics.
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