[Ectothiorhodospira shaposhnikovii respiration when growing in light and in darkness]

The respiration of the purple phototrophic bacterium Ectothiorhodospira shaposhnikovii grown in the light under the anaerobic conditions or in the dark in the presence of oxygen is stimulated with sulfide, NNNN-tetramethyl-p-phenylenediamine (TMPD) + ascorbate and, to a less extent, organic substrates. The electron transport system of the organism is characterized by weak activities of NADH- and NADPH-oxidoreductases and a weak activity of the oxidase region. The respiration of intact cells in the presence of various substrates and the activity of enzymes of the respiration chain in E. shaposhnikovii do not depend on how the cells were grown. The operation of the electron transport chain is not very effective and the citric acid cycle is not closed; these facts seem to account for a low growth rate of E. shaposhnikovii in the dark under the aerobic conditions in organic media.