A molecular mechanism that stabilizes cooperative secretions in Pseudomonas aeruginosa

摘要: Bacterial populations frequently act as a collective by secreting wide range of compounds necessary for cell-cell communication, host colonization and virulence. How such behaviours avoid exploitation spontaneous 'cheater' mutants that use but do not contribute to secretions remains unclear. We investigate this question using Pseudomonas aeruginosa swarming, surface motility requiring massive rhamnolipid biosurfactants. first show swarming is immune the evolution rhlA(-) 'cheaters'. then demonstrate P. resists cheating through metabolic prudence: wild-type cells secrete biosurfactants only when cost their production impact on individual fitness low, therefore preventing non-secreting strains from gaining an evolutionary advantage. Metabolic prudence works because carbon-rich are produced growth limited another limiting nutrient, nitrogen source. By genetically manipulating strain produce constitutively we becomes cheatable: non-producing rapidly outcompetes replaces obligate cooperator. argue prudence, which may evolve direct response or simply optimize growth, can explain maintenance in many bacteria. More generally, prudent regulation mechanism stabilize cooperation.