Growth characteristics of Botryococcus braunii 765 under high CO2 concentration in photobioreactor

To understand the potential of cultivating Botryococcus braunii with flue gas (normally containing high CO2) for biofuel production, growth characteristics of B. braunii 765 with 2–20% CO2 aeration were investigated. The results showed that the strain could grow well without any obvious inhibition under all tested CO2 concentrations with an aeration rate of 0.2 vvm, even without any culture pH adjustment (ranged from 6.0 to 8.0). The maximum biomass among all conditions was 2.31 g L−1 on 25th day at 20% CO2. Hydrocarbon content and algal colony size increased with the increase of CO2 concentration. A negative correlation between algal biomass and culture total phosphorus was observed (from −0.828 to −0.911, P < 0.01). Additionally, 2% sodium hypochlorite solution was used for photobioreactor sterilization to cultivate B. braunii.