Respiratory Enzyme Systems in Symbiotic Nitrogen Fixation: III. The Dehydrogenase Systems of Rhizobium trifolii and Rhizobium leguminosarum.

Earlier studies on the respiratory systems in symbiotic nitrogen fixation (Wilson, 1938) indicated that the root nodule bacteria (Rhizobium spp.) reduce methylene blue anerobically in the presence of many organic compounds. With few exceptions, the efficiency of a given substrate as a hydrogen donator was approximately the same whether molecular oxygen or methylene blue was used as the hydrogen acceptor. Except for short reports by Konishi and Kawamura (1938) and by Kroulik and Gainey (1940) the dehydrogenase systems of the root nodule bacteria have not been extensively investigated. The present report deals with the behavior of the dehydrogenase systems of these bacteria under various physical and chemical conditions. METHODS