Influence oftheBradyrhizobium japonicum Hydrogenase on the GrowthofGlycine andVignaSpecies

Theeffect oftheBradyrhizobiumjaponicum onnitrogen fixation wasevaluated bycomparing the growth ofVignaandGlycine species inoculated with aHupmutantanditsHup+revertant. Inallexperiments, thegrowthofplants inoculated withthestrain without hydrogenase was atleast equal tothegrowth ofthe strain withhydrogenase. ForGlycine usuriensisandGlycine max cv.Hodgson inliquid culture, thegrowth was higher withtheHup-strain. Itispossible thatreduced rates ofnitrogen fixation inthepresenceofhydrogenase aredueto02 depletion caused bythehydrogen oxidizing, sincetheoxygenpressureintheairappearstobe a limiting factor ofsymbiotic nitrogen fixation inthesoybean.