Reciprocal signaling between quorum sensing mutants: A model for division of labor.

Division of labor, the specialization of subsets of individuals in complementary tasks, increases population efficiency and fitness. We explored swarming motility in <i>Pseudomonas aeruginosa</i> quorum sensing mutants as a model for studying the division of labor. Deletion of the signal synthesis genes <i>lasI</i> or <i>rhlI</i> disrupts swarming, but co-culturing <i>ΔlasI</i> and <i>ΔrhlI</i> restores it in a density-dependent manner. This indicates a successful division of labor where <i>ΔrhlI</i> produces the signal necessary for the <i>ΔlasI</i> mutant, and the <i>ΔlasI</i> reciprocates. We used RNA sequencing to identify additional genes potentially involved in division of labor. Our findings underscore <i>P. aeruginosa</i> swarming as a tractable bacterial model for the division of labor among cells-a hallmark of differentiated multicellularity.