UV Mutagenesis, Ammonium-tolerant Strain Selection And Culture Condition Optimization Of Haematococcus Pluvialis

Astaxanthin, a pigment of high antioxidant activity, has important applications in nutraceutical, cosmetics and feed industries. Haematococcus pluvialis, a unicellular green alga has the aility to accumulate astaxanthin under adverse conditions and is the richest source of natural astaxanthin. The selection of H.pluvialis which suit commercial production has been one of the hotspots in the field in recent years.The problems in the process of cultivation are as follows:One is that H.pluvialis have a long growth cycle, the other one is that H.pluvialis are susceptible to contamination.We filtrated a strain, as the parent strain, by single clone method. Then the strain was radiated in ultraviolet light. The lethal rates were calculated and the optimum dose was 5min. We got a strain of mutants from clones.compraed with parent strain, the growth rate was increased and it can survive under 400mg/L NH4HCO3. And rotifers can not survive under this concentration.We have examined the light intensity, NaNO3 concentration, NaCl concentration and temperatures on accumulation of astaxanthin of parent strain and mutant strain H.pluvialis. By analyzing the experimental results, we got the optimal combination as follow:light intensity 200μmol·m-2·s-1, NaNO3 concentration 0mg/L, NaCl concentration 2g/L, and temperatures 27℃.The most suitable foster situation of wild type and mutant strain H.pluvialis was studied. We have exanined the concentration of NaNO3, KH2PO4, FeCl3·6H2O and temperature, light intensity, pH on the best culture condition of the growth of the two strains. It showed that the wild type strain has biggest growth rate at NaNO3 500mg/L, KH2PO4 100mg/L, FeCl3·6H2O 1.0mg/L, temperature 18℃, light intensity 100μmol·m-2·s-1, pH 8. And the mutant at NaNO3 100mg/L, KH2PO4 10mg/L, FeCl3·6H2O 1.0mg/L, temperature 18℃, light intensity 100μmol·m-2·s-1, pH 8.