The precursor to acetic acid is the thioester acetyl CoA. The key aspects of the acetogenic pathway are several reactions that include the reduction of carbon dioxide () to carbon monoxide (CO) and the attachment of CO to a methyl group (–CH). The first process is catalyzed by enzymes called carbon monoxide dehydrogenase. The coupling of the methyl group (provided by methylcobalamin) and CO is catalyzed by acetyl-CoA synthase. 
The global reduction reaction of  into acetic acid by  is the following:
:   ΔG° = −95 kJ/mol
while the conversion of one mole of glucose into 3 moles of acetic acid corresponds to a  more exothermic reaction: 
:   ΔG° = −310.9 kJ/mol
However, the energy released by mole of acetic acid produced by each reaction is about the same: −95 kJ/mol for the reduction of  by , and  more for the conversion of glucose into acetic acid  (−104 kJ/mol).