Bacterivorous nematodes decipher microbial iron siderophores as prey cue in predator-prey interactions.

The minimal levels of biological-available iron in the environment impose growth limitation on all living organisms. Microbes often secrete high iron-binding-affinity siderophores at high concentrations for scavenging iron from the iron-limited habitats. However, the high prevalence of siderophores released by bacteria into the environment raises an intriguing question whether this chemical cue can be detected by bacterivorous predators. Here, we show that the bacterivorous Caenorhabditis elegans nematode could employ its chemosensory receptor Odr-10 to detect pyoverdine, an iron siderophore secreted by an environmental bacterium, Pseudomonas aeruginosa . This enabled the nematode predator to migrate toward the prey. Our soil microcosm study showed that the detection of pyoverdine and subsequent feeding of P. aeruginosa prey by C. elegans could lead to the expansion of its population. These results showed that siderophores are a prey chemical cue by predators, with key implications in predator-prey interactions.