A correlation between changes in luminescence decay kinetics and the appearance of a CO2-accumulating mechanism in Scenedesmus obliquus.

In experiments with the unicellular green algae Scenedesmus obliquus a correlation was found between the presence of the CO2-accumulating mechanism and the appearance of polyphasic luminescence decay kinetics. A potentiometric titration method was used to measure and calculate photosynthetic carbon uptake.Polyphasic luminescence decay kinetics was found when the algae showed photosynthetic characteristics typical of algae adapted to low-CO2 conditions. When high-CO2 grown algae were transferred to low-CO2 conditions they gradually developed polyphasic decay kinetics during the first 25-30 minutes. When low-CO2 grown algae were transferred to high-CO2 conditions the polyphasic decay kinetics disappeared. To account for these results a working hypothesis is presented on the basis of the energy requirement for a CO2-accumulating mechanism.