Pseudomonas aeruginosa rhamnolipid micelles deliver toxic metabolites and antibiotics into Staphylococcus aureus

Efficient delivery of toxic compounds to bacterial competitors is essential during interspecies microbial warfare. Rhamnolipids (RLPs) are glycolipids produced by Pseudomonas and Burkholderia species involved in solubilization and uptake of environmental aliphatic hydrocarbons, and perform as biosurfactants for swarming motility. Here we show that RLPs produced by Pseudomonas aeruginosaassociate to form micelles. Using high resolution microscopy, we found that RLPs micelles serve as carriers for self-produced toxic compounds, which they deliver to Staphylococcus aureuscells, thereby enhancing and accelerating S. aureus killing. RLPs also potentiated the activity of lincosamide antibiotics,  suggesting that RLPs micelles may transport not only self-produced, but also heterologous compounds to target competing bacterial species