Copper selects for siderophore-mediated virulence in Pseudomonas aeruginosa
AbstractIron is essential for almost all bacterial pathogens and consequently it is actively withheld by their hosts. The production of extracellular siderophores however enables iron sequestration by pathogens, increasing their virulence. Another function of siderophores is extracellular detoxification of non-ferrous metals. Here, we experimentally link the detoxification and virulence roles of siderophores by testing whether the opportunistic pathogen Pseudomonas aeruginosa displays greater virulence after exposure to copper stress. We incubated P. aeruginosa under different copper regimes for either two or twelve days. Subsequent growth in a copper-free environment removed phenotypic effects, before quantification of pyoverdine production (P. aeruginosa’s primary siderophore) and virulence using the Galleria mellonella infection model. Copper selected for increased pyoverdine production, which was positively associated with virulence. This effect increased with time. We here show a direct link between metal stress and bacterial virulence, highlighting another dimension of the detrimental effects of metal pollution on human health.