Differentiation of the membrane system in cells of Rhodopseudomonas capsulata after transition from chemotrophic to phototrophic growth conditions

Aerobically in the dark grown cultures of Rhodopseudomonas capsulata were shifted to low oxygen partial pressure for 30 min and afterwards to phototrophic conditions (anaerobic, light). During 210 min of adaptation to a phototrophic mode of life the bacteriochlorophyll (BChl) concentration increased 53-fold (doubling time 40 min) and the carotenoid content six fold. Growth was delayed. The light membrane fraction from chemotrophic and induced phototrophic cells contained low concentrations of small photosynthetic units (reaction center+light harvesting BChl B870), and low respiratory activities, especially of succinatecytochrome c oxidase. The heavy membrane fraction, i.e. the intracytoplasmic chromatophore fraction, increased during adaptation approximately 9-fold in surface area per cell, 42-fold in BChl content, 7-fold in reaction center content and 6-fold in the size of the photosynthetic unit.Phospholipid and fatty acid content and patterns changed slightly during adaptation.Non-standard Abbreviations BChl bacteriochlorphyll - R. Rhodopseudomonas