Table 1.

Hydrogen uptake activity with various E. coli BW25113 mutants in complex medium as determined by the oxidized methylviologen-based H₂ uptake assay after 5 min

Strain	Description	Hydrogen uptake
		nmol/min/mg proteina	relative
E. coli BW25113/pBS(Kan)	wild type	94 ± 12	3.3
E. coli BW25113/pBS(Kan)Synhox	wild type + HoxEFUYH	29 ± 7	1
E. coli BW25113 hyaA/pBS(Kan)Synhox	ΔhyaA (defective hydrogenase 1) + HoxEFUYH	59 ± 21	2.0
E. coli BW25113 hyaB/pBS(Kan)Synhox	ΔhyaB (defective hydrogenase 1) + HoxEFUYH	59 ± 6	2.0
E. coli BW25113 hybB/pBS(Kan)Synhox	ΔhybB (defective hydrogenase 2) + HoxEFUYH	73 ± 13	2.5
E. coli BW25113 hybC/pBS(Kan)Synhox	ΔhybC (defective hydrogenase 2) + HoxEFUYH	80 ± 11	2.8
E. coli BW25113 hycE/pBS(Kan)	ΔhycE (defective hydrogenase 3)	25 ± 0.8	0.9
E. coli BW25113 hycE/pBS(Kan)Synhox	ΔhycE (defective hydrogenase 3) + HoxEFUYH	7 ± 2	0.3
E. coli BW25113 hycG/pBS(Kan)Synhox	ΔhycG (defective hydrogenase 3) + HoxEFUYH	10 ± 2	0.4
E. coli BW25113 hyaB hybC/pBS(Kan)	ΔhyaB and ΔhybC (defective hydrogenase 1 and 2)	21 ± 1	0.7
E. coli BW25113 hyaB hybC/pBS(Kan)Synhox	ΔhyaB and ΔhybC (defective hydrogenase 1 and 2) + HoxEFUYH	21.6 ± 0.3	0.8
E. coli BW25113 hyaB hybC hycE/pBS(Kan)	ΔhyaB, ΔhybC, and ΔhycE (defective hydrogenase 1, 2, and 3)	1.8 ± 0.4	0.06
E. coli MC4100/pBS(Kan)	wild type	35 ± 15	2.3
E. coli MC4100/pBS(Kan)Synhox	wild type + HoxEFUYH	15 ± 6	1
E. coli TG1/pBS(Kan)	wild type	16 ± 7	3.3
E. coli TG1/pBS(Kan)Synhox	wild type + HoxEFUYH	5 ± 3	1
E. coli HD705/pBS(Kan)	defective hydrogenase 3	8 ± 1	5.4
E. coli HD705/pBS(Kan)Synhox	defective hydrogenase 3 + HoxEFUYH	2 ± 2	1

Standard deviations shown from one representative experiment with 2 replicates. a IPTG was added for hydrogen uptake (1 mM) assays activity for 6 h in complex medium.