Pyruvate: ferredoxin oxidoreductase (POR; EC ) catalyzes the thia-mine pyrophosphate-dependent oxidative decarboxylation of pyruvate to form acetyl-CoA and CO2 . The thermophilic, obligate chemolithoauto-trophic hydrogen-oxidizing bacterium, Hydrogenobacter thermophilusTK-6, assimilates CO2 via the reductive tricarboxylic acid cycle.