Interspecies secreted surfactants induce emergent motility in Pseudomonas aeruginosa .

In most natural environments, bacteria live in polymicrobial communities where secreted molecules from neighboring species alter bacterial behaviors including motility, but such interactions are understudied. Pseudomonas aeruginosa is a motile opportunistic pathogen that exists in diverse multispecies environments such as the soil and is frequently found in human wound and respiratory tract co-infections with other bacteria including Staphylococcus aureus . Here we show that P. aeruginosa can co-opt secreted molecules from other species for flagellar-based emergent motility. We found that in the presence of exoproducts from S. aureus and other bacteria, P. aeruginosa switched from swarming to an alternative form of motility where it slid and spread on semi-solid surfaces, and it showed similar behavior on hard agar where it was otherwise unable to move. Surfactants from these species were required for the P. aeruginosa emergent motility, and it was also induced by the addition of numerous exogenous biological and synthetic surfactants. Mutant analysis indicated that this motility was similar to a previously described mucin-based P. aeruginosa motility, 'surfing', albeit with divergent regulation. Thus, our study establishes a major P. aeruginosa surfing-like emergent motility where secreted surfactants from the host as well as neighboring bacterial and interkingdom species serve as public goods, allowing P. aeruginosa to access different environmental niches.