FIG 6.

PMF is generated by the anaerobic oxidation of formate in MR-1. (A) The growth curves of MR-1 (circles), the Δfdh triple mutant (squares), the Δatp mutant (triangles), and the Δfdh Δatp mutant (diamonds) were performed in anoxic SBM with 20 mM lactate and 40 mM fumarate. The reported values are the averages from at least three independent experiments, and the error bars represent the SEM. (B and C) Histograms from flow cytometry measurement of red fluorescence intensity using the dye DiOC₂ for MR-1 (B) and the Δfdh mutant (C) in anaerobic SBM containing 20 mM fumarate supplemented with no carbon source (black lines), 10 mM formate (blue lines), 10 mM lactate (red lines), or 10 mM lactate followed by addition of 5 μM CCCP (gray lines). Flow cytometry was performed on three independent cultures for each condition, and representative data are shown.