a) Measurement of the proton motive force (PMF) in WT and narG::tet cells growing on SK media supplemented or not with lactate or malate before and 40 min after addition of 40 mM nitrate (n=3 biological replicates). b) Growth of V. parvula in the presence of 2,4-DNP in SK and SKL media supplemented or not with nitrate (n=4 biological replicates). Growth rates (μmax) were calculated for each growth curve. c) Lactate (n=6 biological replicates) and aspartate (n=3 biological replicates) consumption by WT growing cells was determined in the spent medium 0, 20, 40, and 60 min after the addition of these carbon sources. d) Lactate consumption was assessed as in c using the narG::tet strain (n=4 biological replicates). Data (a-d) represent mean±SEM, analyzed by one-way ANOVA and Tukey’s HSD test (a) or two-sided t-test (b-d) . NS, not significant.