Oxidation states of R. palustris biomass and growth substrates and the H2 yield from each substrate

CompoundFormulaOxidation statebH2 yield (mol H2/100 mol organic C consumed)c
FumarateC4H4O4+118 ± 3d
SuccinateC4H6O4+0.523 ± 1
AcetateC2H4O2021 ± 3
ButyrateC4H8O2−141 ± 10
  • a  Based on the elemental composition of R. palustris 42OL (25).

  • b  Values were determined for each carbon atom as described previously (7, 26) and then averaged by dividing the sum by the number of carbon atoms.

  • c  NifA* cultures were grown in minimal medium with NH4+

  • d  Calculated by grouping fumarate and malate as a single metabolite [i.e., dH2/d(fumarate + malate) × 100/4 carbon atoms]. The H2 yield from fumarate consumed alone would give a value of 12 ± 2.