SECONDARY CAROTENOIDS IN GREEN ALGAE .I. CHEMISTRY OCCURRENCE AND FACTORS CONTROLLING BIOGENESIS OF THESE POLYENES

1. Secondary carotenoids (SC) are defined as carotenoids synthesized by organisms or by parts of them at the end of the growth phase instead of or in addition to the primary carotenoids. 2. The following oxo-derivatives of β-carotene have been identified as SC: 3,3′-dioxi-4,4′-dioxo-β-carotene (astaxanthin); 3-oxi-4,4′-dioxo-β-carotene; 3-oxi-4-oxo-β-carotene; 4,4′-dioxo-β-carotene (canthaxanthin); and 4-oxo-β-carotene (echinenone). The oxipolyenes are esterified. 3. The ability of 164 strains of Chlorophyta (148 Chlorococcales, 15 Volvocales, 1 Siphonales) to produce SC has been tested (Tab. 1). 4. The synthesis of SC takes place within the chloroplast. The production of fatty oils runs synchronously. The SC diffuse into the fat vacuoles, where they become esterified. 5. The synthesis of SC begins after the reduction of growth which is caused especially by nitrogen deficiency. After addition of nitrogen sources the SC disappear and the primary pigments appear again. 6. There is no direct influence of light on the biogenesis of these polyenes. 7. Glucose, acetate, pyruvate, and succinate increase the concentration of primary carotenoids, but not that of the chlorophylls and the SC. The effects of these compounds on the production of SC seem to be indirect. Growth is stimulated and the nitrogen supply is exhausted earlier. Thus the synthesis of SC begins. © 1968 Springer-Verlag.