Effect of CO_2 Concentration on Growth and Photosynthesis of Spirulina platensis

摘要

The effect of different CO_2 concentrations on the growth and photosynthesis of Spirulina platensis NIES 46 was examined in terms of cell growth and photosynthetic parameters. Under 0.01% CO_2, growth stopped after the depletion of the dissolved inorganic carbon and the cell yield was low. The cells grown under 0.07% CO_2 exhibited no change in their growth rate when compared with the 0.03% CO_2-grown culture, yet the cell yield increased from 1.2 to 3.6 g/l. The cells under 1% CO_2 showed the lowest growth, even though the inorganic carbon remained at 50-60 mg/l and pH 7.5-8.0. The photosynthetic rates under 0.03 and 0.07% CO_2 were higher than those under 0.01 or 1%. Accordingly, among the tested CO_2 concentrations, 0.07% CO_2 was found to be the best for a high- density culture of S. platensis NIES 46.