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Pseudomonas aeruginosa PAO1 preferentially grows as aggregates in liquid batch cultures and disperses upon starvation

Pseudomonas aeruginosa PAO1 preferentially grows as aggregates in liquid batch cultures and disperses upon starvation
Pseudomonas aeruginosa PAO1 preferentially grows as aggregates in liquid batch cultures and disperses upon starvation
In both natural and artificial environments, bacteria predominantly grow in biofilms, and bacteria often disperse from biofilms as freely suspended single-cells. In the present study, the formation and dispersal of planktonic cellular aggregates, or ‘suspended biofilms’, by Pseudomonas aeruginosa in liquid batch cultures were closely examined, and compared to biofilm formation on a matrix of polyester (PE) fibers as solid surface in batch cultures. Plankton samples were analyzed by laser-diffraction particle-size scanning (LDA) and microscopy of aggregates. Interestingly, LDA indicated that up to 90% of the total planktonic biomass consisted of cellular aggregates in the size range of 10–400 µm in diameter during the growth phase, as opposed to individual cells. In cultures with PE surfaces, P. aeruginosa preferred to grow in biofilms, as opposed to planktonicly. However, upon carbon, nitrogen or oxygen limitation, the planktonic aggregates and PE-attached biofilms dispersed into single cells, resulting in an increase in optical density (OD) independent of cellular growth. During growth, planktonic aggregates and PE-attached biofilms contained densely packed viable cells and extracellular DNA (eDNA), and starvation resulted in a loss of viable cells, and an increase in dead cells and eDNA. Furthermore, a release of metabolites and infective bacteriophage into the culture supernatant, and a marked decrease in intracellular concentration of the second messenger cyclic di-GMP, was observed in dispersing cultures. Thus, what traditionally has been described as planktonic, individual cell cultures of P. aeruginosa, are in fact suspended biofilms, and such aggregates have behaviors and responses (e.g. dispersal) similar to surface associated biofilms. In addition, we suggest that this planktonic biofilm model system can provide the basis for a detailed analysis of the synchronized biofilm life cycle of P. aeruginosa.
1932-6203
e5513
Schleheck, David
bec76f0f-ff08-471b-953f-50ca0ddc9e91
Barraud, Nicolas
01e480a6-d225-44eb-acde-433c5b24bb82
Ausubel, Frederick M.
8a369642-9f72-48e1-bf5f-f797b01c137a
Klebensberger, Janosch
41a6a6f1-643f-4513-8614-f3d82a919310
Webb, Jeremy S.
ec0a5c4e-86cc-4ae9-b390-7298f5d65f8d
McDougald, Diane
3d3fb9da-5b8f-4170-87ab-167c54592e57
Rice, Scott A.
4f9516db-1d35-4211-878c-bb6cfb2a6b4a
Kjelleberg, Staffan
043b66b5-130c-42f2-99b3-ec3eecf3248e
Schleheck, David
bec76f0f-ff08-471b-953f-50ca0ddc9e91
Barraud, Nicolas
01e480a6-d225-44eb-acde-433c5b24bb82
Ausubel, Frederick M.
8a369642-9f72-48e1-bf5f-f797b01c137a
Klebensberger, Janosch
41a6a6f1-643f-4513-8614-f3d82a919310
Webb, Jeremy S.
ec0a5c4e-86cc-4ae9-b390-7298f5d65f8d
McDougald, Diane
3d3fb9da-5b8f-4170-87ab-167c54592e57
Rice, Scott A.
4f9516db-1d35-4211-878c-bb6cfb2a6b4a
Kjelleberg, Staffan
043b66b5-130c-42f2-99b3-ec3eecf3248e

Schleheck, David, Barraud, Nicolas, Ausubel, Frederick M., Klebensberger, Janosch, Webb, Jeremy S., McDougald, Diane, Rice, Scott A. and Kjelleberg, Staffan (2009) Pseudomonas aeruginosa PAO1 preferentially grows as aggregates in liquid batch cultures and disperses upon starvation. PLoS ONE, 4 (5), e5513. (doi:10.1371/journal.pone.0005513).

Record type: Article

Abstract

In both natural and artificial environments, bacteria predominantly grow in biofilms, and bacteria often disperse from biofilms as freely suspended single-cells. In the present study, the formation and dispersal of planktonic cellular aggregates, or ‘suspended biofilms’, by Pseudomonas aeruginosa in liquid batch cultures were closely examined, and compared to biofilm formation on a matrix of polyester (PE) fibers as solid surface in batch cultures. Plankton samples were analyzed by laser-diffraction particle-size scanning (LDA) and microscopy of aggregates. Interestingly, LDA indicated that up to 90% of the total planktonic biomass consisted of cellular aggregates in the size range of 10–400 µm in diameter during the growth phase, as opposed to individual cells. In cultures with PE surfaces, P. aeruginosa preferred to grow in biofilms, as opposed to planktonicly. However, upon carbon, nitrogen or oxygen limitation, the planktonic aggregates and PE-attached biofilms dispersed into single cells, resulting in an increase in optical density (OD) independent of cellular growth. During growth, planktonic aggregates and PE-attached biofilms contained densely packed viable cells and extracellular DNA (eDNA), and starvation resulted in a loss of viable cells, and an increase in dead cells and eDNA. Furthermore, a release of metabolites and infective bacteriophage into the culture supernatant, and a marked decrease in intracellular concentration of the second messenger cyclic di-GMP, was observed in dispersing cultures. Thus, what traditionally has been described as planktonic, individual cell cultures of P. aeruginosa, are in fact suspended biofilms, and such aggregates have behaviors and responses (e.g. dispersal) similar to surface associated biofilms. In addition, we suggest that this planktonic biofilm model system can provide the basis for a detailed analysis of the synchronized biofilm life cycle of P. aeruginosa.

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Published date: 13 May 2009
Organisations: Centre for Biological Sciences

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Local EPrints ID: 349678
URI: http://eprints.soton.ac.uk/id/eprint/349678
ISSN: 1932-6203
PURE UUID: 096a28f9-1ded-4d6c-8491-98cbc09457a8
ORCID for Jeremy S. Webb: ORCID iD orcid.org/0000-0003-2068-8589

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Date deposited: 11 Mar 2013 10:31
Last modified: 15 Mar 2024 03:26

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Contributors

Author: David Schleheck
Author: Nicolas Barraud
Author: Frederick M. Ausubel
Author: Janosch Klebensberger
Author: Jeremy S. Webb ORCID iD
Author: Diane McDougald
Author: Scott A. Rice
Author: Staffan Kjelleberg

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