The electron transport chain of Bacterionema matruchotii

The membrane fraction of Bacterionema matruchotii contains an electron transport chain with oxidizing activity for NADH and succinate. Respiration was inhibited by KCN, 2-heptyl-4-hydroxyquinoline-N-oxide, UV light irradiation and CO. UV light irradiation, analysis of membrane extracts, and reconstitution of respiration in UV light treated membranes suggested that respiration is mediated by a menaquinone derivative. The membranes contained cytochromes a, b, and c. Inhibition studies and the effect of KCN and CO on the cytochrome spectrum indicated the presence of an a+a3 cytochrome oxidase and cytochrome o. The membrane fraction from cells grown under O2-limiting conditions contained nitrate reductase activity. In B. matruchotii, electron transport is coupled to oxidative phosphorylation as judged by the effects of substrates and inhibitors on the intracellular ATP concentration.