TABLE 3.

Hydrogenase and formate dehydrogenase specific activities in cell extracts of M. hungatei grown syntrophically and in cell extracts of cells grown axenically with H2 or formate as an electron donora

EnzymebSubstrate-dependent sp act (U/mg) with:
Syntrophic growthH2Formate
BV-dependent FDH594.61.7
F420-dependent FDH2.20.0750.35
BV-dependent H2ase6.02.56.5
F420-dependent H2ase3.12.03.3
H2ase (H2 evolution)9.13.69.6
Formate-H2 lyase (cells)2.60.520.56
  • a Syntrophically-grown M. hungatei cells were separated from S. fumaroxidans cells by Percoll gradient centrifugation. Formate-H2 lyase and oxidation activities were measured at 37°C and pH 8. Formate-H2 lyase was measured with intact cells. Methyl viologen-mediated H2 production with dithionite as an electron donor was measured at 37°C and pH 7.

  • b FDH, formate dehydrogenase; H2ase, hydrogenase; BV, benzyl viologen.