Optimization of culture medium for the continuous cultivation of the microalga Haematococcus pluvialis.

TLDR: The high cell productivities obtained with the new optimized medium can serve as a basis for the development of a two-stage technology for the production of astaxanthin from H. pluvialis.

Abstract: The freshwater microalga Haematococcus pluvialis is one of the best microbial sources of the car- otenoid astaxanthin, but this microalga shows low growth rates and low final cell densities when cultured with traditional media. A single-variable optimization strategy was applied to 18 components of the culture media in order to maximize the productivity of vegeta- tive cells of H. pluvialis in semicontinuous culture. The steady-state cell density obtained with the optimized culture medium at a daily volume exchange of 20% was 3.77 AE10 5 cells ml )1 , three times higher than the cell density obtained with Bold basal medium and with the initial formulation. The formulation of the optimal Haematococcus medium (OHM) is (in g l )1 ) KNO3 0.41, Na2HPO4 0.03, MgSO4 AE7H2O 0.246, CaCl2 AE2H2O 0.11, (in mg l )1 ) Fe(III)citrate AEH2O 2.62, CoCl2 AE6H2O 0.011, CuSO4 AE5H2O 0.012, Cr2O3 0.075, MnCl2 AE4H2O 0.98, Na2MoO4 AE2H2O 0.12, SeO2 0.005 and (in l gl )1 )) biotin 25, thiamine 17.5 and B12 15. Vanadium, iodine, boron and zinc were demonstrated to be non-essential for the growth of H. pluvialis. Higher steady-state cell densities were obtained by a three-fold increase of all nutrient concentrations but a high nitrate concentration remained in the culture medium under such conditions. The high cell productivities obtained with the new optimized medium can serve as a basis for the devel- opment of a two-stage technology for the production of astaxanthin from H. pluvialis.