acryloyl-CoA and then reduced toa propionyl-CoA. Per mol acetate formed 2mol lactate have to be reduced to propionate to maintain the redox balance, and hence, the ATP yield is only 0.3mol ATP per mol lactate consumed! The methylmalonyl-CoA pathway, as carried out by the propionic acid bacteria, is energetically more efficient. Again, 1mol lactate is oxidized to acetate giving rise to ATPbutalsotoreducingequivalents.Theelectronsarefed into the reductive branch, which is very interesting from a