FIG 2.

P. aeruginosa mutants with defects high in the QS regulatory system and in the PQS system are unable to kill S. aureus. A total of 10⁴ CFU of the indicated strains was inoculated into LB medium and grown overnight with SA31. Cocultures were initiated as a 1:1 mix of P. aeruginosa and S. aureus. Samples were then taken for serial dilution and plating on Pseudomonas and Staphylococcus isolation agar to determine the number of CFU per milliliter. Experiments were repeated at least three times, with at least three technical replicates.