Abstract
ABSTRACTThe opportunistic human pathogen Pseudomonas aeruginosa is known for exhibiting diverse forms of collective behaviors, like swarming motility and biofilm formation. Swarming in P. aeruginosa is a collective movement of the bacterial population over a semisolid surface, but specific swarming signals are not clear. We hypothesize that specific environmental signals induce swarming in P. aeruginosa. We show that under nutrient-limiting conditions, a low concentration of ethanol provides a strong ecological motivation for swarming in P. aeruginosa strain PA14. Ethanol serves as a signal and not a source of carbon under these conditions. Moreover, ethanol-driven swarming relies on the ability of the bacteria to metabolize ethanol to acetaldehyde using a periplasmic quinoprotein alcohol dehydrogenase, ExaA. We found that ErdR, an orphan response regulator linked to ethanol oxidation, is necessary for the transcriptional regulation of a cluster of 17 genes, including exaA, during swarm lag. Further, we show that P. aeruginosa displays characteristic foraging motility on a lawn of Cryptococcus neoformans, a yeast species, in a manner dependent on the ethanol dehydrogenase ErdR and on rhamnolipids. Finally, we show that ethanol, as a volatile, could induce swarming in P. aeruginosa at a distance, suggesting long-range spatial effects of ethanol as a signaling molecule.
Highlights
The opportunistic human pathogen Pseudomonas aeruginosa is known for exhibiting diverse forms of collective behaviors, like swarming motility and biofilm formation
To understand the extrinsic cues that induce swarming in P. aeruginosa populations, we sought to investigate the transcriptional response of bacteria during the swarm lag
Our analyses of the transcriptome of bacteria in the early and late phases of swarm lag uncovered the critical role of the periplasmic ethanol oxidation machinery controlled by the response regulator ErdR in P. aeruginosa swarming
Summary
The opportunistic human pathogen Pseudomonas aeruginosa is known for exhibiting diverse forms of collective behaviors, like swarming motility and biofilm formation. Swarming in P. aeruginosa is a collective movement of the bacterial population over a semisolid surface, but specific swarming signals are not clear. We demonstrate the importance of a specific environmental cue, ethanol, produced by many microbes, in inducing swarming in the P. aeruginosa population during starvation. On a semisolid nutritionally defined surface, the opportunistic human pathogen Pseudomonas aeruginosa exhibits a characteristic flagellum-driven locomotory social trait called swarming [3]. Specific environmental signals that serve as ecological motivations for swarming in bacteria remain a poorly understood facet of this form of collective behavior. Do specific environmental signals induce the formation and extension of tendrils, a characteristic of P. aeruginosa swarming? Broad or nutrient-specific starvation might be essential for bacteria to engage in swarming
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
