The Effects of Acetate and CO2 Supplements for Cell Growth of Haematococcus pluvialis in Bubble Column Photobioreactors

초록

Haematococcus pluvialis was cultured autotrophically and mixotrophically for astaxanthin production in bubble column photobioreactors with CO2 and/or acetate supplements. Four different schemes were tested using 5% CO2 balanced with 95% N2 at the aeration rate of 0.1 vvm and supplementation of acetate (1 g/L) to the basal medium, MBBM. Average specific growth rates based on cell total volume of each case were 0.138 day-1 in control (without CO2 and acetate supplements), 0.125 day-1 with only acetate supplementation, 0.315 day-1 with only CO2 supplement, 0.304 day-1 with both CO2 and acetate. The growth rate under CO2 supply was much higher than that without CO2 supply. DCO and DO seemed to be a possible limitation factor. Another interesting observation was the growth rate under CO2 supplement (without acetate) was higher than that under both CO2 and acetate supply. This result is the opposite of the previously reported works. From the result, the existence of acetate may suppress the dark reaction of CO2 fixation or photosynthesis. Conclusively, the growth of H. pluvialis under photoautotrophic condition found to be higher than that under mixotrophic condition.