Figure 2.

Phenazine redox cycling in P. aeruginosa PA14 ∆phz1/2. Cells were grown aerobically in LB to an OD₅₀₀ of 2.8 and then pelleted, washed, and resuspended in anoxic MOPS-buffered minimal medium with 20 mM glucose. Where noted in the ‘potential’ column of the legend, cultures also included 75 µM PCA and an electrode poised at a potential to oxidize any reduced PCA. Results are typical of at least three independent experiments. (A) Survival of strains with deletions of pyruvate metabolism genes. 100% survival represents approximately 7 × 10⁸ CFU/mL. (B) HPLC traces from culture supernatants after three days of phenazine cycling as in panel A. Peaks were identified by comparing retention times to known standards. The dashed gray arrow indicates the retention time of lactate, which was not observed in this experiment. Question marks (?) indicate unidentified products. Asterisks (*) indicate trace contaminants that were present from the start of the experiment.