Haematococcus pluvialis bioprocess optimization: Effect of light quality, temperature and irradiance on growth, pigment content and photosynthetic response

The effect of light quality, using narrow bandwidth light-emitting diode (LED) light sources, irradiance and temperature on the production of green and red cells of Haematococcus pluvialis was studied. The basal optimum conditions selected for astaxanthin accumulation included nitrate starvation, continuous illumination and carbon supply. Monochromatic red light at 20 degrees C was optimal for green cell production, while astaxanthin accumulation rate was maximal with mixed red and blue light at 30 degrees C. Under these conditions, astaxanthin productivity reached 25 mg L-1 day(-1). Irradiance affected astaxanthin content, but it did not affect the increase in dry weight. The photosynthetic response of H. pluvialis was characterized as complex and highly dependent on the conditions in which the alga is being produced, specially light composition. The use of LEDs for tuning light composition is proven to be a powerful tool to enhance metabolite production.