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Red cyst cells of algae Haematococcus pluvialis were cultivated in liquid culture, under controlled condition of growth chamber (in 100 ml of medium) or outdoor (in 8 liter of medium), to examine the effect of nitrogen forms on growth and ketocarotenoid astaxanthin formation.
Short period experiment, under growth chamber conditions, showed that nitrate-grown algae produce more astaxanthin than the ammonium-grown algae. Within 2-weeks of cultivation, use of ammonum-N, made algae growing as green vegetative cells and these cells do not produce astaxanthin. However, during the successive vegetation periods the green vegetative cells induce encystment and carotenogenesis, which may be due to nutrient deficiency. Within 32 days of cultivation, ammonium-grown algae yield more cells and astaxanthin. Maximum cell numbers obtained only by the use of ammonium phosphate. Also after using different ammonium salts. The trasformation from green motile cells into red cysts are influenced severly by incubation time. This may be due to the difference in time necessary for establishing changes cell constitution and activities, which are associated with nitrogen and phosphorus nutrition.