TABLE 1.

Thiosulfate:cytochrome c oxidoreductase activities in periplasmic extracts of R. sulfidophilum strains

Strain	Culture conditions (electron donor, carbon source)a	Assay supplementb	Mean activity [nmol of cytochrome c reduced min−1 (ml of periplasmic extract)−1]
Parental 3.1	S2O32−, HCO3−		12 ± 2
	S2O32−, malate		27 ± 3
	None, malate		3.5 ± 0.5
soxA::Gmr	S2O32−, malate		NDc
	S2O32−, malate	SoxAX	18 ± 3
soxA::Ω	S2O32−, malate		ND
	S2O32−, malate	SoxAX	9 ± 1

^aCells were harvested at an optical density at 650 nm in the range of 0.8 to 1.3. 

^bAssays were supplemented with 20 μg of cytochrome c₅₅₁ complex per ml where indicated. 

^cND, nondetectable.