During glycolysis NADH2 is formed, and most organismscontainanNADH2:ferredoxinoxidoreductase.However, the redox potential of the NAD/NADH2 couple (E0’52320mV) is too electropositive to allow reduction of protons (E0’ H1/H2 52414mV) but this reaction becomes thermodynamically feasible if the hydrogen formed is taken out of the equilibrium. In nature, this is achieved by interspecies hydrogen transfer in microbial consortia in which hydrogen-consuming bacteria oxidize