Abstract
A strain of blue green alga, Cyanidium caldarium GEITLER, was isolated from the sample material collected from a hot spring in Yumoto, Nikko, Japan. Consistent subcultures were obtained and the growth responses of the organism towards various environmental conditions were investigated.
The alga was found to be markedly thermophilic and extremely acidophilic in nature, most favorable growth taking place at 45°-50° and pH 3.0. The changes in the metabolic activities of the organism during the course of culture were followed.
The effect of hydrogen ion concentration, temperature, light intensity and carbon dioxide concentration on the rate of photosynthesis was investigated. The optimum hydrogen ion concentration was pH 3.0. The optimum temperature lied at 55°. The apparent heat of activation (in respect to the dark reaction of photosynthesis) amounted to 17 Kcal for the temperature range 55°-40°, and 7 Kcal for 40°-30° (pH 3.0). The saturating intensity of the light was found to be about 105 Lux or higher with sufficient amount of carbon dioxide in the medium. Under sufficiently strong illumination, the half-saturation of photosynthesis was reached at a concentration of carbon dioxide of ca. 1.2×10-4 mol/l (or about 0.6% CO2 in air: pH 3.0, 45°). These findings were compared with the data reported for the green alga, Chlorella.
