The steady-state internal redox state (NADH/NAD) reflects the external redox state and is correlated with catabolic adaptation in Escherichia coli

The steady-state internal redox state in prokaryotes was investigated by growing Escherichia coli MC4100 in anaerobic glucose-limited cultures in the presence of an electron acceptor or fully fermentatively. The steady-state NADH/NAD ratio was found to be dependent on the nature of external electron acceptors. Results also showed that the synthesis and activity of the pyruvate dehydrogenase complex occur under anaerobic respiratory conditions and correlate with the cellular steady-state redox state.