TABLE 1.

H2 production by nongrowing R. palustris cells using thiosulfate or organic acids as electrons donors

StrainElectron donor (20 μmol)Bicarbonate concn (mM)Amt (μmol)a% electron donor oxidizedaH2 yield (% of theoretical maximum)a,b
Electrons donatedH2 produced (μmol)Electrons in H2 (μmol)
Wild typeThiosulfate056 (8)16 (10)32 (20)35 (4)56 (20)
Thiosulfate0.5126 (22)45 (6)90 (12)79 (14)71 (4)
Thiosulfate2.0157 (2)61 (2)122 (4)98 (7)78 (2)
Thiosulfate4.0146 (10)56 (4)112 (8)92 (7)77 (14)
NifA*Thiosulfate0144 (5)62 (3)124 (6)90 (3)86 (1)
Thiosulfate0.5152 (2)56 (6)112 (12)96 (2)73 (6)
Thiosulfate2.0152 (3)31 (3)62 (6)97 (2)40 (4)
Wild typeAcetate0160 (0)34 (14)68 (28)100 (0)c43 (18)
Succinate0280 (0)83 (15)166 (30)100 (0)c59 (11)
None2.03 (1)6 (2)
None02 (1)4 (2)
  • a Data reported are the averages of two to four determinations ± standard deviations (in parentheses).

  • b The maximum theoretical yield of H2 from thiosulfate or acetate is 4 mol H2/mol electron donor, and that from succinate it is 7 mol H2/mol electron donor. The percentage of the theoretical maximum yield is calculated from the amount of H2 gas produced from substrate consumed.

  • c Substrate was oxidized below our detection limit of 10 nmol.