Proton motive force in washed cells of Rhizobium japonicum and bacteroids from Glycine max.

The components of the proton motive force (delta p), namely the membrane potential and the transmembrane pH gradient, were measured in washed cells of Rhizobium japonicum CC705 grown in cultures (5% O2-95% N2) in the presence of 10 mM KNO3 and in bacteroids from Glycine max. The delta p and its components remained reasonably constant in cells as well as in bacteroids at various stages of growth. The effects of uncouplers and ATPase inhibitors on the delta p and its components were determined in both cultured cells and bacteroids. The data indicated that a respiration-driven H+ translocation is the source of the delta p in both cultured cells and bacteroids.