FIG. 5.

Wild-type P. aeruginosa PA14 excretes pyruvate in stationary phase, and addition of pyocyanin to Δphz mutant cultures restores the pyruvate excretion phenotype. Cultures were inoculated into MOPS synthetic medium amended with 50 mM glucose (initial optical density at 500 nm, 0.03). To complement pyruvate excretion, 50 μM pyocyanin was added to the Δphz culture at the time when pyocyanin reached its maximum concentration in the wild-type cultures (approximately 12 h after inoculation). Twenty microliters of culture filtrates at the 24-hour time point was loaded onto an anion-exchange column and subjected to an isocratic gradient in 5 mM H₂SO₄. Pyruvate peaks are indicated by arrows. The elution time of pyruvate drifts slightly but averages around 10.5 min. Results shown are representative of three separate experiments. Other peak identities are described in the text. wt, wild type; PYO, pyocyanin.