Cell death in pseudomonas aeruginosa biofilm development

• Main Authors: Webb, Jeremy S. (Author), Thompson, Lyndal S. (Author), James, Sally (Author), Charlton, Tim (Author), Tolker-Nielsen, Tim (Author), Koch, Birgit (Author), Givskov, Michael (Author), Kjelleberg, Staffan (Author)
• Format: Article
• Language: English
• Published: 2003-08.
• Subjects: Article
• Online Access: Get fulltext

 Bacteria growing in biofilms often develop multicellular, three-dimensional structures known as microcolonies. Complex differentiation within biofilms of <i>Pseudomonas aeruginosa</i> occurs, leading to the creation of voids inside microcolonies and to the dispersal of cells from within these voids. However, key developmental processes regulating these events are poorly understood. A normal component of multicellular development is cell death. Here we report that a repeatable pattern of cell death and lysis occurs in biofilms of <i>P. aeruginosa</i> during the normal course of development. Cell death occurred with temporal and spatial organization within biofilms, inside microcolonies, when the biofilms were allowed to develop in continuous-culture flow cells. A subpopulation of viable cells was always observed in these regions. During the onset of biofilm killing and during biofilm development thereafter, a bacteriophage capable of superinfecting and lysing the <i>P. aeruginosa</i> parent strain was detected in the fluid effluent from the biofilm. The bacteriophage implicated in biofilm killing was closely related to the filamentous phage Pf1 and existed as a prophage within the genome of P. aeruginosa. We propose that prophage-mediated cell death is an important mechanism of differentiation inside microcolonies that facilitates dispersal of a subpopulation of surviving cells.