This work was supported by the Cystic Fibrosis Foundation CFF grant number RIBBEC08I0 and MIT startup funds to K.R. K.R.F. is supported by European Research Council grant 242670. R.S.F. is supported through the National Science Foundation Graduate Research Fellowship Program. We thank D.J. Wozniak for the EPS deletion strains, B. Berwin for providing the P. aeruginosa PA14 strains, W. Kim for the labeled conjugating strain, G.A. O’Toole for the complementation vector, and the lab of R. Kolter for the E. coli strain ZK2686.