Oxygen-induced inhibition of light-dependent uptake of tetraphenylphosphonium ions as a probe of a direct interaction between photosynthetic and respiratory components in cells of Rhodopseudomonas capsulata.

Light-generated and oxygen-dependent membrane potentials by heterotrophycally grown cells of Rhodopseudomonas capsulata have been investigated by using a tetraphenylphosphonium ion-selective electrode. The results show that respiratory electron transport affects the magnitude of photogenerated membrane potential while photosynthesis seems to either inhibit or stimulate respiration in coupled or uncoupled cells, respectively. These observations have been considered as evidence that the intracytoplasmic membrane system of R. capsulata contain respiratory and photosynthetic apparatuses which are strictly intermingled.