Table 1.

Hydrogen-oxidizing enzyme activity of the feoB::Tn5 mutant PM06 grown in minimal medium with different iron sources

Strain and iron supplementa	Hydrogenase specific activityb (μmol H2 oxidized min-1 mg protein-1)
	MC4100	PM06 (feoB::Tn5)
no iron addition	2.02 ± 0.64	0.49 ± 0.19
7.5 μM iron chloride (FeCl3)	3.63 ± 0.73	2.49 ± 0.64
15.3 μM hemin	1.72 ± 0.92	0.25 ± 0.18
10 μM potassium ferrocyanide (K4[Fe(CN)6]) (Fe2+)	1.34 ± 1.30	0.38 ± 0.33
10 μM potassium ferricyanide (K3[Fe(CN)6]) (Fe3+)	1.80 ± 2.82	0.93 ± 0.85
10 μM ferric ammonium sulfate (Fe(NH4)(SO4)2)	3.33 ± 2.53	2.02 ± 2.11
50 μM iron citrate (C6H5FeO7)	2.20 ± 0.70	3.47 ± 1.17
300 μM 2,2'-dipyridyl	< 0.01	< 0.01
300 μM 2,2'-dipyridyl and 200 μM FeCl3	0.04 ± 0.07	< 0.01
300 μM 2,2'-dipyridyl and 200 μM iron citrate	1.59 ± 1.16	0.04 ± 0.06

^a Cells were cultivated in M9 minimal medium including 0.8% (w/v) glucose. Iron sources were added at the given final concentrations.

^b The activities were determined for triplicate experiments.