Dunaliella salina is a type of halophile pink micro-algae especially found in sea salt fields. Known for its anti-oxidant activity, 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.
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 to Oren's knowledge no biotechnological operation presently (July 2005) exists that exploits the alga for glycerol production.
Did the Ancients commercially exploit Dunaliella salina?
Pliny refers to flos salis,"The best kind of it (flower of salt) yields a sort of oily fat, for there is, surprisingly as it may seem, a fat even in salt....a kind of salt rust" (Nat His. 31 90). We may be reasonably confident that flos salis refers to a concentrated mush largely composed of the remains of the alga Dunaliella salina. Pliny says of flos salis "In vessels the whiteness is seen on the surface but the inner part, as I have said, is moister." A mush of glycerol and salt-saturated brine is likely to deposit white salt on its container as water evaporates. If the brine is heavily pigmented this phenomenon would be extremely striking. Flos salis was widely used in the Roman perfume industry. According to Pliny it was for the colour but the glycerol, as a solvent, was probably more significant.
For more on the last 100 years of Dunaliella 
Aharon Oren 2005 A hundred years of Dunaliella research: 1905–2005 Saline Systems 1: 2. Published online 2005 July 4. doi: 10.1186/1746-1448-1-2. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.