12-methyltetradecanoic acid, a branched-chain fatty acid, represses the extracellular production of surfactants required for swarming motility in pseudomonas aeruginosa PAO1

Tetsuyoshi Inoue, Teruo Kuroda, Naoya Oohara

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3 Citations (Scopus)


Pseudomonas aeruginosa is known to produce surfactants that are involved in its swarming motility behavior, such as rhamnolipids and their precursors-3-(3-hydroxyalkanoyloxy) alkanoic acids (HAAs). In P. aeruginosa PAO1, swarming motility is inhibited by some fatty acids, including branched-chain fatty acids and unsaturated fatty acids. In the present study, addition of 12- methyltetradecanoic acid (12-MTA, anteiso-C15:0) to an agar medium markedly repressed surfactant activity in the extracellular fraction of a P. aeruginosa culture in a drop collapse assay. Further, an extracellular fraction of a culture of rhlA mutant P. aeruginosa, which did not produce both rhamnolipids and HAAs, showed a complete loss of surfactant activity and markedly reduced swarming activity. In contrast, an extracellular fraction of a culture of rhlB mutant P. aeruginosa, which produced HAAs but not rhamnolipids, showed moderate swarming activity and weak extracellular surfactant activity that was lost on the addition of 12-MTA to the agar medium. Expression of the rhlAB operon from the plasmid pMR2 restored normal swarming motility on 12-MTA-containing agar medium. Taken together, these findings indicate that 12-MTA reduced extracellular surfactant activity, thus resulting in a swarming defect in P. aeruginosa PAO1.

Original languageEnglish
Pages (from-to)126-131
Number of pages6
JournalJapanese Journal of Infectious Diseases
Issue number2
Publication statusPublished - 2012


ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases

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