High efficiency production of astaxanthin by autotrophic cultivation of Haematococcus pluvialis in a bubble column photobioreactor

Haematococcus pluvialis was cultivated under photoautotrophic conditions in a bubble column with fed-batch addition of nutrients, especially nitrate, and a cell number above 5 × 10⁶ cells mL^?1 was attained after 300 h.The reduction of nutrient concentrations accompanied by dilution of the fermentation broth and an increase in the light intensity enhanced accumulation of astaxanthin. The final astaxanthin concentration of 390 mg L^?1 was several times higher than ever reported. This combination of fed-batch addition of nutrients and dilution of broth for nutrient deficiency is a promising method for attainment of high cell and astaxanthin concentrations in a bubble column photobioreactor.