Spoils of war: iron at the crux of clinical and ecological fitness of Pseudomonas aeruginosa

Pseudomonas aeruginosa is a versatile environmental microorganism that also causes life-threatening opportunistic infections. At the root of this bacterium's ability to survive in such diverse environments is its large suite of iron acquisition systems. More recently, studies have highlighted the ability of P. aeruginosa to compete with other organisms for this essential metallonutrient. This minireview provides an overview of the iron acquisition systems used by P. aeruginosa, with an emphasis on how these systems contribute to fitness in polymicrobial environments. We also provide an evolutionary perspective of how these systems were selected for in the native habitats of the Pseudomonads, while also highlighting factors that are unique to P. aeruginosa.