The reductive acetyl CoA pathway (CoA) pathway, also known as the Wood-Ljungdahl pathway uses CO2 as electron acceptor and carbon source, and H2 as an electron donor to form acetic acid. See Carbon Fixation.
The Carbon Monoxide Dehydrogenase/Acetyl-CoA Synthase is the oxygen-sensitive enzyme that permits the reduction of CO2 to CO and the synthesis of in several reactions.