Changes in Chlorophyll a/b Ratio and Products of 14CO2 Fixation by Algae Grown in Blue or Red Light

Chlamydomonas and Chlorella were grown for 10 days in white light. 955 muw/cm(2) blue light (400-500 mmu) or 685 muw/cm(2) red light (above 600 mmu). Rates of growth in blue or red light were initially slow, but increased over a period of 5 days until normal growth rates were reestablished. During this adaptation period in blue light, total chlorophyll per volume of algae increased 20% while the chlorophyll a/b ratio decreased. In red light no change was observed in the total amount of chlorophyll or in the chlorophyll a/b ratio. After adaptation to growth in blue light and upon exposure to (14)CO(2) with either blue or white light for 3 to 10 minutes, 30 to 36% of the total soluble fixed (14)C accumulated in glycolate-(14)C which was the major product. However, with 1 minute experiments, it was shown that phosphate esters of the photosynthetic carbon cycle were labeled before the glycolate. Glycolate accumulation by algae grown in blue light occurred even at low light intensity. After growth of the algae in red light, (14)C accumulated in malate, aspartate, glutamate and alanine, whereas glycolate contained less than 3% of the soluble (14)C fraction.