Growth of the photosynthetic bacterium Rhodopseudomonas capsulata chemoautotrophically in darkness with H2 as the energy source

Abstract

The phototrophic bacterium R. capsulata was capable of growing chemoautotrophically under aerobic conditions in darkness. Growth was strictly dependent on the presence of H2 as the source of energy and reducing power, O2 as the terminal electron acceptor for energy transduction, and CO2 as the sole C source; under optimal conditions the generation time was about 6 h. Chemoautotrophically grown cells showed a relatively high content of bacteriochlorophyll a and intracytoplasmic membranes (chromatophores). Experiments with various mutants of R. capsulata, affected in electron transport, indicate that either of the 2 terminal oxidases of this bacterium can participate in the energy-yielding oxidation of H2. The ability of R. capsulata to multiply in at least 5 different physiological growth modes suggests that it is 1 of the most metabolically versatile prokaryotes known.