Fig. 4
Cellular electron demand and electron supply in PCC6803 under different steady state conditions. Rates are given in µmol electrons mg −1CDW day−1. PCC6803 was grown with ammonium (gray bars) or nitrate (white bars) as N sources under LLHC (low light high carbon), HLHC (high light high carbon), and HLLC (high light low carbon) conditions. Growth conditions are described in the legend of Fig. 2. Photosystem II electron supply rates are derived from gross O2 evolution rates (rO,gross) and reflected by the entire column heights, whereas electron consumption rates for carbon (striped from lower left to upper right) and nitrate (striped from upper left to lower right) assimilation are shown as shares of the overall supply rates. Mean values and standard deviations were calculated for three different measurement days. See “Materials and methods” for details on the measurements