Rhamnolipids Modulate Swarming Motility Patterns ofPseudomonas aeruginosa

Top Cited Papers
Open Access
Publisher Website
Google Scholar
Abstract
Pseudomonas aeruginosais capable of twitching, swimming, and swarming motility. The latter form of translocation occurs on semisolid surfaces, requires functional flagella and biosurfactant production, and results in complex motility patterns. From the point of inoculation, bacteria migrate as defined groups, referred to as tendrils, moving in a coordinated manner capable of sensing and responding to other groups of cells. We were able to show thatP. aeruginosaproduces extracellular factors capable of modulating tendril movement, and genetic analysis revealed that modulation of these movements was dependent on rhamnolipid biosynthesis. AnrhlBmutant (deficient in mono- and dirhamnolipid production) and anrhlCmutant (deficient in dirhamnolipid production) exhibited altered swarming patterns characterized by irregularly shaped tendrils. In addition, agar supplemented with rhamnolipid-containing spent supernatant inhibited wild-type (WT) swarming, whereas agar supplemented with spent supernatant from mutants that do not make rhamnolipids had no effect on WTP. aeruginosaswarming. Addition of purified rhamnolipids to swarming medium also inhibited swarming motility of the WT strain. We also show that asadBmutant does not sense and/or respond to other groups of swarming cells and this mutant was capable of swarming on media supplemented with rhamnolipid-containing spent supernatant or purified rhamnolipids. The abilities to produce and respond to rhamnolipids in the context of group behavior are discussed.