Lake Retba, Lac Rose, Dakar, Senegal

Dunaliella salina
Dunaliella salina is a type of halophile green micro-algae especially found in sea salt fields. Known for its anti-oxidant activity because of its ability to create large amount of carotenoids, it is used in cosmetics and dietary supplements. Few organisms can survive in such highly saline conditions as salt evaporation ponds. To survive, these organisms have high concentrations of β-carotene to protect against the intense light, and high concentrations of glycerol to provide protection against osmotic pressure. This offers an opportunity for commercial biological production of these substances.
From a first pilot plant for Dunaliella cultivation for β-carotene production established in the USSR in 1966, the commercial cultivation of Dunaliella for the production of β-carotene throughout the world is now one of the success stories of halophile biotechnology. Different technologies are used, from low-tech extensive cultivation in lagoons to intensive cultivation at high cell densities under carefully controlled conditions. Although Dunaliella salina produce β-Carotene in a high salt environment, archaea such as Halobacterium, not Dunaliella, are responsible for the red and pink coloring of salt lakes. Occasionally, orange patches of Dunaliella colonies will crop up.
Attempts have been made to exploit the high concentrations of glycerol accumulated by Dunaliella as the basis for the commercial production of this compound. Although technically the production of glycerol from Dunaliella was shown to be possible, economic feasibility is low and no biotechnological operation presently (July 2005) exists that exploits the alga for glycerol production.