Influence of stress on astaxanthin production in Haematococcus pluvialis grown under different culture conditions

The influence of stress was studied on astaxanthin production in Haematococcus pluvialis grown under different culture conditions. High concentrations of NaCl (>1.0% w/v) were lethal and the age of the culture was crucial for stress induced astaxanthin production. Four to-eight-day-old cultures were sensitive to NaCl addition while older cultures (12–16 days) were resistant. Older cells accumulated 8.3–10.69 mg/l astaxanthin compared to 0.95–8.1 mg/l in 4–8-day-old cultures, respectively. Cultures grown with calcium nitrate as nitrogen source showed a significant increase in astaxanthin content and production under stress compared to other nitrogen sources. Similarly, cultures grown at pH 7.0 showed more astaxanthin production than those grown at pHs of 6.0, 8.0 and 9.0.