Redox chain and energy transduction in chromatophores from Rhodopseudomonas capsulata cells grown anaerobically in the dark on glucose and dimethyl sulfoxide

Membranes from cells of Rhodopseudomonas capsulata grown anaerobically in the dark on glucose plus dimethyl sulfoxide differ from those obtained from photoheterotrophically grown cells in several ways: (a) there are qualitative and quantitative variations in the cytochrome composition; (b) electron-transport rates are unusually low in the cytochrome b to cytochrome c region; (c) light-induced ATP synthesis is dependent on the ability of the alternate respiratory pathway to maintain the Q₁₀-cytochrome b complex in a partially oxidized state; (d) a non-energy-conserving NADH-dehydrogenase activity dominates the respiratory activity. In addition, data obtained with both wild-type and mutant cells that contain altered electron-transport systems tend to exclude a role of the redox chain as ATP-producing machinery during anaerobic/dark growth.