Proposed metabolic role of P. furiosus ADH. Abbreviations: Fdox, oxidized ferredoxin; Fdred, reduced ferredoxin; KAOR, α-keto acid ferredoxin oxidoreductases; CoASH, coenzyme A; AOR, aldehyde ferredoxin oxidoreductase; ACS, acetyl-CoA synthetases; FNOR, ferredoxin NADP oxidoreductase; SH, sulfhydrogenase (or hydrogenase).