초록
The addition of CO<SUB>2</SUB> to algal culture systems can increase algal biomass effectively. Generally, gas bubbling is used to increase CO<SUB>2</SUB> levels in culture systems; however, it is difficult to quantitatively operate to control the concentration using this method. In this study, we tested the usability of CO<SUB>2</SUB> hydrate for phytoplankton culture. Specifically, green algae Pseudokirchneriella subcapitata were cultured in COMBO medium that contained dissolved CO<SUB>2</SUB> hydrate, after which its effects were evaluated. The experiment was conducted according to a general bioassay procedure (OECD TG201). CO<SUB>2</SUB> promoted algae growth effectively (about 2-fold relative to the control), and the decrease in pH due to dissolution of the CO<SUB>2</SUB> in water recovered soon because of photosynthesis. Since the CO<SUB>2</SUB> hydrate method can control a CO<SUB>2</SUB> concentration easily and quantitatively, it is expected to be useful in future applications.