Effect of Blue Light on CO₂ Fixation in Heterotrophically Grown Scenedesmus obliquus Mutant C-2A′

Abstract

It has been established that blue light enhances respiration in various algae (for literature, see Voskresenskaya 1972). With colorless mutant and wild type cells of Chlorella vulgaris as well as Chlorella ellipsoidea, Miyachi and coworkers found that blue light also enhanced CO₂ incorporation into aspartate (Ogasawara and Miyachi 1970; Kamiya and Miyachi 1974; Miyachi et al. 1979). The characteristics of both blue light effects were very similar, indicating that the same mechanism underlies blue light-induced respiration and CO₂ fixation. With heterotrophically-grown wild type and mutant C-2A′ cells, Watanabe et al. (1979) found that ¹⁴CO₂ -incorporation was enhanced upon illumination with fluorescent lamps. In this paper it was proved that blue light caused an enhancement of ¹⁴CO₂-incorporation in the mutant cells of Scenedesmus. In the case of Chlorella cells, ¹⁴CO₂-fixation was enhanced immediately the blue light was switched on, while respiration was enhanced only after a lag period of several minutes. However, in mutant cells of Scenedesmus, both respiration and ¹⁴CO₂ fixation were enhanced immediately blue light illumination commenced. A possible explanation for such difference was discussed.