Energy transduction in Propionibacterium acnes
1. Propionibacterium acnes was shown to be sensitive to valinomycin thus enabling the membrane potential (∆Ψ) generated under a variety of conditions to be measured by determining the distribution of K⁺ across the membrane in the presence of valinomycin. 2. Under anaerobic conditions, both anaerobically- and aerobically-grown P. acnes generated a ∆Ψ of approximately -140 mV. Oxygen stimulated the generation of the ∆Ψ in both anaerobically- and aerobically-grown cells. The effect of inhibitors of oxidative phosphorylation on the ∆Ψ generated was studied. 3. Anaerobically- and aerobically-grown P. acnes were capable of uncoupler-stimulated respiration. The effect of various inhibitors on respiration was studied. 4. Respiration-driven H⁺ translocation was demonstrated in both anaerobically- and aerobically-grown P. acnes. The →H⁺/O ratios obtained were consistent with the presence of one coupling site on the electron transport chain. The effect of inhibitors on respiration-driven H⁺ translocation was studied. 5. Anaerobically- and aerobically-grown P. acnes contained cytochromes b, a₁, d and o. 6. Attempts to characterize the ATPase from P. acnes and to demonstrate its sensitivity to classical energy-transfer inhibitors were unsuccessful. 7. Using the results obtained from the various approaches, a role for oxygen in the energy transduction process of P. acnes was proposed.