[Inhibitory analysis of the respiration of bacteroids from the nodules of yellow lupine]

Abstract

Oxygen uptake and reduction of C2H2 by bacteroids was found to be inhibited by low concentrations of cyanide and azide. However, oxygen uptake was not completely suppressed even by 10(-3) M KCN. Cyanide-resistant respiration was not inhibited by salicyl-hydroxamic acid, and seemed to be accomplished at the account of autoxidable flavo-proteins. A small light-reversible inhibition of respiration by carbon monoxide was found only in the bacteroids with a high rate of nitrogen fixation. Rotenone, antimycin A, and tenoyltrifluoroacetone inhibited oxygen uptake and methylene reduction. Nitrogen fixation, but not respiration, was inhibited by 2,4-dinitrophenol. An electron-transport chain coupled with phosphorylation is supposed to be built into the membranes of the bacteroids. The activity of peroxidase and cytochrome peroxidase was demonstrated in the bacteroids.