Figure 4.

β-galactosidase activity from the ydfZ promoter in anaerobically grown wild-type, Δfnr, and ΔiscSUAhscBAfdx (Δisc), and ΔiscSUAhscBAfdx, ΔsufABCDSE (Δisc, Δsuf) strains. The ΔiscSUAhscBAfdx strain derivatives contained either the plasmid expressing the sufABCDSE operon from the arabinose-inducible P_BAD promoter (pSuf), the vector alone, or no vector. All cultures were grown anaerobically in M9 minimal glucose medium containing nicotinic acid (12.5 μg ml⁻¹). The plasmid-containing strains were also grown in the presence of ampicillin (final concentration of 50 μg ml⁻¹) and, where indicated, 0.2% arabinose.