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Self‐produced extracellular stimuli modulate the Pseudomonas aeruginosa swarming motility behaviour
Author(s) -
Tremblay Julien,
Richardson AnnePascale,
Lépine François,
Déziel Eric
Publication year - 2007
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/j.1462-2920.2007.01396.x
Subject(s) - swarming (honey bee) , swarming motility , tendril , biology , motility , extracellular , pseudomonas aeruginosa , chemotaxis , biophysics , microbiology and biotechnology , biofilm , bacteria , biochemistry , quorum sensing , ecology , genetics , receptor
Summary Pseudomonas aeruginosa presents three types of motilities: swimming, twitching and swarming. The latter is characterized by rapid and coordinated group movement over a semisolid surface resulting from morphological differentiation and intercellular interactions. A striking feature of P. aeruginosa swarming motility is the formation of migrating tendrils producing colonies with complex fractal‐like patterns. Previous studies have shown that normal swarming motility is intimately related to the production of extracellular surface‐active molecules: rhamnolipids (RLs), composed of monorhamnolipids (mono‐RLs) and dirhamnolipids (di‐RLs), and 3‐(3‐hydroxyalkanoyloxy) alkanoic acids (HAAs). Here, we report that (i) di‐RLs attract active swarming cells while HAAs behave as strong repellents, (ii) di‐RLs promote and HAAs inhibit tendril formation and migration, (iii) di‐RLs and HAAs display different diffusion kinetics on a surface as di‐RLs spread faster than HAAs in agar, (iv) di‐RLs and HAAs have no effect on swimming cells, suggesting that swarming cells are different from swimming cells not only in morphology but also at the regulatory level and (v) mono‐RLs act as wetting agents. We propose a model explaining how HAAs and di‐RLs together modulate the behaviour of swarming migrating cells by acting as self‐produced negative and positive chemotactic‐like stimuli.