Characterization of starvation-induced dispersion dispersion in Pseudomonas putida biofilms.
Environ Microbiol. 2005 Jun;7(6):894-904.
Morten Gjermansen, Paula Ragas, Claus Sternberg, Søren Molin, and Tim Tolker-Nielsen* Molecular Microbial Ecology Group, DTU Systems Biology, Technical University of Denmark, DK-2800 Lyngby, Denmark. *ttn@sund.ku.dk
Abstract: The biofilm lifestyle, where microbial cells are aggregated due to expression of cell-to-cell interconnecting compounds, is believed to be of paramount importance to microbes in the environment. Since microbes must be able to alternate between sessile and planktonic states, it is anticipated that they must be able to regulate their ability to form biofilm and to dissolve biofilm. We present an investigation of a biofilm dissolution process occurring in flow-chamber-grown Pseudomonas putida biofilms. Local starvation-induced biofilm dissolution appears to be an integrated part of P. putida biofilm development that causes characteristic structural rearrangements. Rapid global dissolution of entire P. putida biofilms was shown to occur in response to carbon starvation. Genetic analysis suggested that the adjacent P. putida genes PP0164 and PP0165 play a role in P. putida biofilm formation and dissolution. PP0164 encodes a putative periplasmic protein of previously unknown function, and PP0164 mutant bacteria are sticky, and unable to reduce their adhesiveness and dissolve their biofilm in response to carbon starvation. PP0165 encodes a putative transmembrane protein containing GGDEF and EAL domains, and PP0165 mutant bacteria are unable to increase their adhesiveness and form biofilm. We suggest that the PP0164 and PP0165 proteins are involved in the regulation of the adhesiveness of the bacteria; the PP0165 protein through c-di-GMP signalling, and the PP0164 protein as a transducer of the signal.
Nutrient limitation induced dispersion of Pseudomonas putida OUS82 Tn7GFP biofilm (3D projection of CLSM micrograph).
The biofilm was cultivated in flowchamber for 3 days in AB minimal media supplemented with 1mM Na-citrate, before subjecting it to flowstop or shift to a media without a carbonsource.
Time scale of the movie is approx. 10 min. Images was captured with a Zeiss LSM510 confocal laser scanning microscope.
Film (uncompressed AVI, 14.6Mb)
Nutrient limitation induced dispersion of Pseudomonas putida OUS82 fliM mutant biofilm (3D projection of CLSM micrograph)
The biofilm was cultivated in flowchamber for 3 days in AB minimal media supplemented with 1mM Na-citrate, before subjecting it to flowstop or shift to a media without a carbonsource.
Time scale of the movie is approx. 10 min. Images was captured with a Zeiss LSM510 confocal laser scanning microscope.
Film (uncompressed AVI, 12.6Mb)
Nutrient limitation induced dispersion of Pseudomonas putida OUS82 Tn7GFP wt biofilm (Video microscopy)
The cells are leaving the biofilm as single cells in a process that is accompanied by rapid swimming.
Film (uncompressed AVI, 30.3Mb)
Nutrient limitation induced dispersion of Pseudomonas putida OUS82 fliM mutant biofilm (Video microscopy)
The cells are leaving the biofilm as single cells but no swimming is observed.
Film (uncompressed AVI, 25.7Mb)
Nutrient limitation induced dispersion of Pseudomonas putida OUS82 fliM mutant biofilm (CLSM z-slice)
Dispersion initiates in the center of the biofilm structure and proceeds outwards.