Figure 1. Respiration impacts L. monocytogenes growth and fermentative output.

(A) Proposed respiratory electron transport chains in L. monocytogenes. Different NADH dehydrogenases likely transfer electrons to distinct but presently unidentified quinones (Q_a and Q_b). FmnB catalyzes assembly of essential components of the electron transport chain, PplA and FrdA, that can transfer electrons to ferric iron and fumarate, respectively. Other proteins involved in the terminal electron transfer steps are noted. (B) Optical density of L. monocytogenes strains aerobically grown in nutrient-rich media, with the anaerobically grown wildtype strain provided for context. The means and standard deviations from three independent experiments are shown. (C) Fermentation products of L. monocytogenes strains grown to stationary phase in nutrient-rich media under aerobic and anaerobic conditions. Error bars show standard deviations. Results from three independent experiments are shown. (D) Proposed pathways for L. monocytogenes sugar metabolism. The predicted number of NADH generated (+) or consumed (−) in each step is indicated. PplA, peptide pheromone-encoding lipoprotein A; FrdA, fumarate reductase; ΔQC, ΔqoxA/ΔcydAB; ΔQC/fmnB, ΔqoxA/ΔcydAB/fmnB::tn; GLC, glucose; Ack, acetate kinase; Pdh, pyruvate dehydrogenase; Pfl, pyruvate formate-lyase; DMK, demethylmenaquinone.

Figure 1—figure supplement 1. Use of respiratory electron acceptors enhances Listeria monocytogenes growth in nutrient-rich media.

(A) Optical density of L. monocytogenes strains grown anaerobically in nutrient-rich media. The data represent the means and standard deviations from three independent experiments. (B) Optical density of anaerobically grown strains in nutrient-rich media supplemented with the alternative electron acceptors ferric iron (Fe³⁺) or fumarate (fum), as indicated. The means and standard deviations from three independent experiments are shown.