In addition to being the major end product, ethanol is
the byproduct of many fermentations. Many lactic acid
bacteria, enterobacteria and clostridia form considerable
amounts of ethanol as a reduced end product to maintain
their redox balance. In these cases, acetyl-CoA is reduced
via acetaldehyde to ethanol by acetaldehyde dehydrogenase
and ethanol dehydrogenase, respectively.