High-density culture of Haematococcus pluvialis in bubble column photobioreactors with CO2 and nitrate supplements

초록

High-density culture of Haematococcus pluvialis for astaxanthin production was performed in bubble column photobioreactors with CO2 and nitrate supplements. The initial conditions of the photobioreactors were working volume of 450 mL in modified MBBM medium, light intensity of 40 mmol/m2s, and 0.1 vvm aeration with CO2 enriched air. Whenever the nitrate level was lower than 20% of the initial level, a fresh medium with concentrated nitrate was fed. We obtained the final cell concentration of 2.2 ´ 107 cell/L, dry cell weight of 5.0 g/L (fresh cell weight of 20.5 g/L), and astaxanthin concentration of 250 mg/L after induction by high light intensity when the culture reached stationary phase. These values were higher than most of recently reported data. When there was no CO2 supplement, maximal cell concentration was much lower even though acetate was fed in order to achieve mixotrophic culture condition. The final cell concentration under this mixotrophic condition was about 5 ´ 106 cell/L (dry cell weight of 2.8 g/L) and the final astaxanthin concentration was 64 mg/L.