Cultivation of Haematococcus pluvialis in airlift bioreactor

Abstract

The production of Haematococcus pluvialis NIES-144 was investigated in this experiment. The F1 medium (Fabregas et al., 1998) with a vitamin B complex supplement at 12 microgram/L was shown to yield the highest cell density of H.pluvialis. The cultivation of this alga in the 3L airlift bioreactor was proven to be superior to that in the bubble column of the same size operated at the same aeration rate. CO[subscript 2] was important for a better growth of the alga. The operation with a mixture of air and 1% CO[subscript 2] at the superficial gas velocity of 0.4 cm/s was found to give the highest cell growth. No appreciable effect of the ratio between the downcomer and riser cross sectional areas in the airlift system was observed in this work, however, the higher area ratio was selected as it required less power consumption in aeration. The light intensity for the highest growth rate was found to be at 20 micromol photon m[superscript -2] s[superscript-1]. A semi-continuous culture could be achieved where the harvest was performed at every 4 days. The specific growth rate and productivity in semi-continuous culture were 0.31 day[superscript 1] and 5.52 cell mL[superscript -1] day[superscript -1], respectively. The potential of inducing astaxanthin from H.pluvialis was tested where light intensity and the nutrient composition were found to significantly affect the accumulation of astaxanthin