THE EFFECT OF NUTRITIONAL STRESSES ON ACCUMULATION OF ASTAXANTHIN IN HAEMATOCOCCUS PLUVIALIS

Haematococcus pluvialis was induced to accumulate astaxanthin by altering nutritional conditions. The experiment of N-limited condition showed that the rate of astaxanthin accumulation was inversely proportional to the initial nitrogen concentration and to the rate of cell division. When the concentration of nitrogen in BBM mediun was reduced from 0.25g. L-1 to 0.13g·L-1, a higher rate of cell division and astaxanthin accumulation was relatively favourable. Under starvation of nitrogen or phosphate, the cell division of H. pluvialis was inhibited, but astaxanthin accumulation was enhanced with 141.0% and 60.5% higher content than the controls respectively. The maximum astaxanthin accumulation occurred 2-4 days earier than the control. This induction did not occur under salt stress condition where NaCl concentration increased to 0.8%. The experiments also showed that the astaxanthin accumulation was not totally associated with the formation of akinete. Under nitrogen starvation condition, the motile cells were found to accumulate large amount of red pigment.