TABLE 4.

Levels of spectral complexes and β-galactosidase activities in R. sphaeroides strains grown under aerobic conditions^a

Strain	Plasmid	Level (nmol/mg of protein) of:		Activity (nmol/min/mg of protein) of strain carrying puf::lacZ
		B800–850	B875
2.4.1	pRK415	0.05 ± 0.02	0.00 ± 0.00	72 ± 9
PrrB1	pA-9	0.13 ± 0.01	1.36 ± 0.01	251 ± 5
PrrB1	pUI1649	0.02 ± 0.01	0.11 ± 0.01	53 ± 3

^aStrains carrying the corresponding plasmids were grown aerobically by sparging with 30% O₂–69% N₂–1% CO₂ to an optical density of 600 nm of 0.4 to 0.5. For determination of promoter activities of the puf operon, strains carrying puf::lacZ transcriptional fusion plasmid pUI1663 were grown aerobically by sparging with 30% O₂–69% N₂–1% CO₂ to an optical density of 600 nm of 0.3 to 0.35. All values are the averages of two independent determinations.