Abstract
A blue green alga, Chroococcus sp., was cultivated continuously and the kinetics of metabolism were determined for major nurients.
Bottom mud from a small agricultural pond in Ube city was taken into a cultivation jar and algae were precultivated. Alga, Chroococcus sp., was transfered to a continuous cultivator which is of the net volume of 13.8 dm3, thermostated at 30°C, and applied light with 8 white spotlights of 200W. The culture medium contained NaHCO3, NaNO3, KH2PO4, MgSO4, CaCl2, FeCl3 and EDTA. The pH value was kept at 8.0. The alga cell concentration was kept at 3, 000 to 4, 000 mg/dm3. Under these condition, the alga growth rate was 11.4 g-dry biomass/m2-light applied area/day.
The uptake rates, which were determined with batch method, for hydrogen carbonate, nitrate and phosphate ions in light were 3.4 × 10-2, 5.3 × 10-3 and 5.8 × 10-4 g/g-dry biomass/day and the uptake rate for oxygen in the dark was 2.7 × 10-3 and the excreting rate for phosphate ion was 8.2 × 10-6. The relative ratio of nutrient uptake rate with batch method was reasonably in agreement not only with that calculated from mass balance in continuous cultivation but with element content ratio of alga.
