Figure 5. Fermentation fluxes are increased when an anode is provided as an extracellular electron acceptor.

Results are from the same set of experiments as the current density plot shown in Figure 3C. (A) Metabolic yields of L. plantarum end-fermentation products under open circuit conditions (OC) and current circulating conditions (EET) in mCDM supplemented with 20 μg/mL DHNA. (B) pH measurements and (C) mannitol, (D) lactate, (E) acetate, and (F) ethanol concentrations over time under OC and EET conditions. (G) Schematic of proposed model for NADH regeneration during fermentation of mannitol in the presence of an anode as electron sink for L. plantarum. The avg ± stdev of three biological replicates is shown. Significant differences were determined by one-way ANOVA with Dunn-Sidak post-hoc (n = 3), ** p < 0.01. See also Figure 5—figure supplement 1 and Figure 5—figure supplement 2 and related data in Figure 5—source data 1.

Figure 5—figure supplement 1. EET by L. plantarum is not dependent on aerobic or anaerobic respiration components.

(A) Effect on L. plantarum current production with heme addition to reconstitute the aerobic electron transport chain. (B) Effect on L. plantarum current production with the deletion of the nitrate reductase A. The anode was polarized to +0.2 V (vs Ag/AgCl sat. KCl). The avg± stdev of two biological replicates is shown. See related data in Figure 5—figure supplement 1—source data 1.

Figure 5—figure supplement 2. EET by L. plantarum does not involve TCA cycle metabolites.

Succinate, formate and pyruvate produced under EET (solid line) and open-circuit (dashed line) conditions from Figure 5. The avg± stdev of three biological replicates is shown. See related data in Figure 5—figure supplement 2—source data 1.