Photoxidation Processes in Normal Green Chlorella Cells

The authors describe the kinetics of pigment bleaching in Chlorella cells exposed to very intense light (100,00 lux). They distinguish two phases: an induction phase preceding bleaching, and a bleaching phase. Both phases require oxygen. During the bleaching phase, carotene disappears, then chlorophyll (a), and finally chlorophyll (b) and the carotenols. The induction of bleaching is dark-reversible and seems to reflect important changes in the cell metabolism. It has been suggested that the induction is concerned with some modifications of the properties of the chloroplast proteins that are essential for the stability of the pigments.