Cultivation – Red Stage

In the red stage, the culture is subjected to environmental and nutrient stress. With exposure to high irradiation and changes in the nutrient media such as deprivation of nitrate and phosphate or addition of sodium chloride, the cells form thick walled cysts. They synthesize and accumulate astaxanthin in the esterified form. Within 2 to 3 days after the culture is stressed, haematocysts are formed and begin accumulating astaxanthin; within 3 to 5 days following the formation of haematocysts (containing ~1-3% astaxanthin), they are ready for harvest.