Which archaeon is known for surviving in saturated salt solutions?

Halobacterium salinarum is an archaeon known for surviving and growing in saturated salt solutions.

Despite its name, H. salinarum is not a bacterium: it belongs to the domain Archaea. It is an extreme halophile found in salterns, hypersaline lakes, salted fish, hides, and other intensely salty environments. Its pink or reddish color comes largely from carotenoid pigments and light-sensitive membrane proteins.

The organism manages salt stress by accumulating potassium ions inside the cell, helping balance the sodium-rich environment outside. Its proteins are unusually acidic, which helps them remain dissolved and functional where ordinary proteins would precipitate. H. salinarum can also use bacteriorhodopsin, a light-driven proton pump, when dense salt-pond populations deplete available oxygen.

Sulfolobus and Pyrococcus are also extremophilic archaea, but they specialize in different conditions: Sulfolobus favors hot, acidic habitats, while Pyrococcus thrives in very hot, often oxygen-free environments. “Halobacterium” is therefore an old name that can mislead readers about the organism’s classification.