Effect of Light Conditions in the Culture Vessel on the Chlorophyll Content and Photosynthetic Rate of Spirulina.

Abstract

The oxygen regeneration system is one of the most important subsystems for Closed Ecological Life Support Systems (CELSS). In order to construct an oxygen regeneration system by culturing algae, it is important to know the relationship between the amount of oxygen generated and the culture conditions. From the results of culture experiments with Spirulina platensis, a common blue-green alga for CELSS, it was found that the chlorophyll content of Spirulina varied with the cell density, that is, light conditions in the culture vessel. This suggests that the photosynthetic ability of Spirulina varies with the light conditions. In this study, the net photosynthetic rate of Spirulina was measured, and the effect of light conditions on the photosynthetic rate was investigated. From the results of the measurements, it was clear that the chlorophyll content and relationship between net photosynthetic rate and light intensity varied with the light conditions. Furthermore, when the net photosynthetic rate was represented on a chlorophyll content basis, the relationship between net photosynthetic rate and light intensity was the same relationship for all three cell densities tested.