Effect of culture supernatants, obtained at various optical densities, on photosynthetic membrane production (A) and cell growth (B) of R. rubrum. A: PM production during microaerobic cultivation using sterile filtered culture supernatants and cells harvested from an aerobic Fed-Batch cultivation. Black bars represent production in cells harvested from the Fed-Batch cultivation, washed and resuspended in fresh medium. White bars indicate cells harvested from an aerobic pre-culture, washed and resuspended in supernatant from the same Fed-Batch cultivation. B: Initial growth rate under microaerobic conditions after cells were inoculated into filtered culture supernatant harvested from the same aerobic Fed-Batch cultivation. As a control for both A and B, cells harvested from an aerobically grown preculture were washed and resuspended in fresh medium (striped bars). Rates were calculated from data during the growth phase of the cultivation. The shown data represents the mean of three measurements. Error bars were calculated by error propagation with accumulated deviations of three equivalent experiments. (Cells and culture supernatants from three Fed-Batch cultivations were treated as described above).