Question: Escherichia coli can generate energy under anaerobic growth conditions by fermentation, convertin…

Escherichia coli can generate energy under anaerobic growth
conditions by fermentation, converting glucose to a mixture of
ethanol and lactate. Under these conditions, the F1Fo ATP synthase
is not required for ATP synthesis. Instead, the enzyme runs in
reverse, hydrolyzing ATP and pumping protons out of the cell across
the cytoplasmic membrane. This is a strategy that appears to waste
ATP, so what is the physiological rationale for the ATP synthase
running backwards when ATP is being made by fermentation?