An additional group of bacteria that produce ethanol, acetate and lactate as fermention products are the Enterobacteria.  They use glucose as their growth substrate and produce ATP by substrate level phosphorylation generating pyruvate by glycolysis.  Pyruvate can then be used as an electron sink directly, producing lactate, or it can be cleaved by the enzyme pyruvate formate lyase generating acetyl CoA and formate.

The formate is oxidized by NAD to yield CO2 in a reaction catalysed by an enzyme complex called formate hydrogen lyase. Hydrogen is formed by subsequent oxidation of the reduced NAD catalysed by a hydrogenase component of the complex. The hydrogen is released as a waste product and can serve as a growth substrate for homoacetogens and methanogens.

A proportion of acetyl CoA produced by the pyruvate formate lyase reaction that is not needed for biosynthetic purposes is converted either to acetaldehyde, (which is then converted to ethanol; both reactions regenerating NAD) or to acetyl phosphate. This latter reaction is catalysed by phosphotransacetylase.  Acetyl phosphate then yields ATP, in a reaction catalysed by acetate kinase; generating acetate as the waste end product. This metabolic profile is called mixed acid fermentation.

The functional link between pyruvate formate lyase, phosphotransacetylase and acetate kinase has led to identification of this sequence as the "phosphoroclastic cleavage" pathway for generating ATP from pyruvate.

The following scheme shows mixed acid fermentation in Enterobacteria.