TABLE 4.

Promoter activities of hemZ and hemN in R. sphaeroides FNRL and CCOP1FNRL mutants grown under aerobic conditions^a

Strain	β-Galactosidase activity (nmol/min/mg of protein)
	hemZ::lacZ	hemN::lacZ
FNRL	5.2 ± 2.0	52.1 ± 1.8
CCOP1FNRL	5.2 ± 1.0	195.2 ± 1.4

^aStrains were grown aerobically by sparging with 30% O₂–69% N₂–1% CO₂ to an OD₆₀₀ of 0.4 to 0.5. Plasmids pJE3170 and pUI2762 carrying transcriptional fusions hemZ::lacZ and hemN::lacZ, respectively, were used to determine promoter activities of the corresponding gene. All values are the averages of two independent determinations.