Pseudomonas aeruginosa uses type III secretion system to kill biofilm-associated amoebae

Carsten Matz*, Ana Maria Moreno, Morten Alhede, Mike Manefield, Alan R. Hauser, Michael Givskov, Staffan Kjelleberg

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

87 Scopus citations

Abstract

Bacteria and protozoa coexist in a wide range of biofilm communities of natural, technical and medical importance. Generally, this interaction is characterized by the extensive grazing activity of protozoa on bacterial prey populations. We hypothesized that the close spatial coexistence in biofilms should allow opportunistic pathogenic bacteria to utilize their eukaryote-targeting arsenal to attack and exploit protozoan host cells. Studying cocultures of the environmental pathogen Pseudomonas aeruginosa and the amoeba Acanthamoeba castellanii, we found that P. aeruginosa rapidly colonized and killed biofilm-associated amoebae by a quorum-sensing independent mechanism. Analysis of the amoeba-induced transcriptome indicated the involvement of the P. aeruginosa type III secretion system (T3SS) in this interaction. A comparison of mutants with specific defects in the T3SS demonstrated the use of the secretion apparatus and the effectors ExoU, ExoS and ExoT in the killing process, of which ExoU had the greatest impact. T3SS-mediated virulence towards A. castellanii was found to be controlled by the global regulators RpoN and RpoS and through modulation of cAMP and alginate biosynthesis. Our findings suggest that conserved virulence pathways and specifically the T3SS play a central role in bacteria-protozoa interactions in biofilms and may be instrumental for the environmental persistence and evolution of opportunistic bacterial pathogens.

Original languageEnglish (US)
Pages (from-to)843-852
Number of pages10
JournalISME Journal
Volume2
Issue number8
DOIs
StatePublished - Aug 2008

Keywords

  • Acanthamoeba
  • Bacteria-protozoa interactions
  • Conserved virulence
  • Transcriptome

ASJC Scopus subject areas

  • Microbiology
  • Ecology, Evolution, Behavior and Systematics

Fingerprint Dive into the research topics of 'Pseudomonas aeruginosa uses type III secretion system to kill biofilm-associated amoebae'. Together they form a unique fingerprint.

Cite this