Fig. 9

Schematic diagram of electron transfer chain in B. subtilis. Electrons are extracted under action of NADH dehydrogenase and formate. MK-7 and cytochrome c act as electron transport carriers, and finally electrons are delivered to oxygen to form water (A). Membrane potential evaluated by Flow cytometry of dead cell (Control), BS168 and SinR^quad (B). Changes in the membrane potential evaluated by mean fluorescence intensity (MFI), total NAD content, NADH content yield and NADH/NAD⁺ ratio in BS168 and SinR^quad (C). Expression level of NADH dehydrogenase of SinR^quad, compared with BS168; positive numbers mean upregulation; negative numbers mean downregulation (D). Catalytic reaction of NADH reduction in cells, including l-lactate dehydrogenase (ldH), (R,R)-butanediol dehydrogenase (bdhA), NADH dehydrogenase (ndH), aerobic glycerol-3-phosphate dehydrogenase (glpD), and succinate dehydrogenase flavoprotein (sdhABC) (E). All experiments were independently carried out at least three times, and the results were expressed as mean ± standard deviation (SD)