Abstract
Non-axenic laboratory cultures and mixed-species microcosms were used to assess the limiting factors to growth and carotenogenesis in the halophilic green alga Dunaliella salina. Growth is inhibited at low temperatures, especially night-time temperatures. N03 is the best form of N, while NH4N0 3 leads to cell death. Fe-citrate is the best form of Fe for growth. In .order to control protozoan predation cultures must be grown at salinities >17% NaCl (w/v) with 20% NaCl being optimal for growth and carotenoid content. Adequate nutrients must also be supplied.