Changes in Chlorophyll a/b Ratio and Products of CO(2) Fixation by Algae Grown in Blue or Red Light

Chlamydomonas and Chlorella were grown for 10 days in white light. 955 μw/cm² blue light (400-500 mμ) or 685 μw/cm² red light (above 600 mμ). 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 ¹⁴CO₂ with either blue or white light for 3 to 10 minutes, 30 to 36% of the total soluble fixed ¹⁴C accumulated in glycolate-¹⁴C 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, ¹⁴C accumulated in malate, aspartate, glutamate and alanine, whereas glycolate contained less than 3% of the soluble ¹⁴C fraction.