FIG 1.
Metabolic pathway of ethanol biosynthesis in C. ljungdahlii. Abbreviations used: Pta, pta, phosphotransacetylase; Ack, ack, acetate kinase; AdhE, adhE, aldehyde/alcohol dehydrogenase; AOR, aor, acetaldehyde:ferredoxin oxidoreductase; PFOR, pfor, pyruvate:ferredoxin oxidoreductase; LdhA, ldhA, lactate dehydrogenase; ALDC, aldc, acetolactate decarboxylase; 23BDH, bdh, 2,3-butanediol dehydrogenase; Fdred, reduced ferredoxin; Fdox, oxidized ferredoxin; Nfn, electron-bifurcating and ferredoxin-dependent transhydrognenase; Rnf complex, membrane-associated and energy-conserving reduced ferredoxin:NAD+ oxidoreductase. The Rnf-ATPase system is a system of two enzyme complexes in which the Rnf complex generates a proton gradient across the membrane by the oxidation of Fdred with NAD+. The second enzyme complex, the ATPase complex, consumes the proton gradient and phosphorylates ADP to ATP in the cytoplasm. AdhE pathway, ethanol formation by AdhE catalysis; AOR pathway, AOR participates in acetate and ethanol formation.