Nitrogenase-Mediated H2 Production by Rhodopseudomonas Capsulata. Role of Uptake Hydrogenase in the Efficiency of H2 Production

Abstract

As in other N2 fixers, the hydrogenase of R. capsulata functions as an uptake hydrogenase. It is an intrinsic membrane protein with a high affinity for H2 (K H2 M = 0.2 µM) (Colbeau, Vignais, 1981) and a true component of the respiratory chain. It has recently been shown, with the use of hydrogenase antibodies, to be oriented towards the cytoplasmic compartment (Colbeau et al., 1983) and to contain Ni (Colbeau, Vignais, 1983). The role of uptake hydrogenase in the efficiency of H2 production by Rhodopseudomonas capsulata has been studies as follows: 1. Isolation and biochemical characterization of hydrogen uptake-deficient (Hup−) mutants. 2. Comparison of the efficiencies of H2 production by the Hup− mutants and wild type strain, B10. 3. Analysis of the relationship between hydrogenase activity and nitrogenase activity in continuous culture.