Studies on red pigments excreted by cells of Chlorella protothecoides during the process of bleaching induced by glucose or acetate. I. Chemical properties of the red pigments

During the process of bleaching of Chlorella protothecoides cells induced by the addition of glucose or acetate in a nitrogen-deficient mineral nutrient medium, at least four red pigments were found to be excreted into the incubation medium. These pigments were separated by thin-layer chromatography on silica gel, and their absorption spectra in visible and infrared regions as well as their NMR spectra were measured. Elementary composition and the Gmelin colour reaction of the pigments were also examined. The results obtained suggest that the four pigments are certain acidic substances—containing a structure similar to that of a bile pigment—which are most probably derived from chlorophyll through oxidative rupture of the tetrapyrrole ring of the latter.