Light and carbon limited photosynthesis of Chlorella sorokiniana

Carbon dioxide (CO2) and light are essential for high photosynthetic rates of microalgal cultures. Microalgal photosynthetic behavior at low CO2 concentrations has not been revealed yet at the same level of detail as leaf photosynthesis. In the present study, we investigated the short-term photosynthetic response of suspended Chlorella sorokiniana to limiting light intensity and CO2 concentration. We used a novel CO2-based photosynthesis monitor originating from leaf research but equipped with an aquatic chamber sparged with CO2 enriched air. Photosynthesis was measured by employing a steady-state CO2 mass balance over the chamber. Light and carbon response curves were determined under constant pH, temperature, dissolved oxygen, light intensity or dissolved carbon dioxide. We determined the volumetric mass transfer coefficient of the aquatic chamber to accurately convert gaseous CO2 partial pressure into aqueous CO2 concentration to evaluate the CO2 response measurements.