TABLE 3.

Intracellular NADH and NAD⁺ concentrations in C. acetobutylicum wild type and rex-inactivated mutant^a

Strain	Addition to cultures	NADH concn (mM)	NAD+ concn (mM)	NADH/NAD+ ratio
Wild type		0.19 ± 0.01	0.83 ± 0.01	0.23 ± 0.02
Wild type	MV	0.27 ± 0.03	0.46 ± 0.01	0.59 ± 0.05
Wild type	H2O2	0.20 ± 0.02	1.11 ± 0.11	0.18 ± 0.02
rex mutant		0.26 ± 0.02	1.02 ± 0.18	0.25 ± 0.02
rex mutant	MV	0.34 ± 0.08	0.38 ± 0.07	0.92 ± 0.11
rex mutant	H2O2	0.16 ± 0.02	1.44 ± 0.12	0.11 ± 0.02

^aData represent means ± standard deviations of nine measurements from three biological replicates. The strains were grown in the P2 minimal medium without or with addition of 1 mM MV or 30 μM H₂O₂. The intracellular concentrations of NADH and NAD⁺ were determined in the exponential growth phase at an OD₆₀₀ of about 2.0.