Halophiles

AbstractHalophiles are salt‐loving organisms that flourish in saline environments and can be classified as slightly, moderately or extremely halophilic, depending on their requirement for sodium chloride. Although most marine organisms are slight halophiles, moderate and extreme halophiles are generally more specialised microbes, which inhabit hypersaline environments with salinity higher than in the sea. Hypersaline environments are found all over the world, in arid, coastal, and deep‐sea locations, underground salt mines, and artificial salterns. Halophilic microorganisms include a variety of heterotrophic, phototrophic, and methanogenic archaea, photosynthetic, lithotrophic, and heterotrophic bacteria, and photosynthetic and heterotrophic eukaryotes. Examples of well‐adapted and widely distributed extremely halophilic microorganisms include archaea for example,Halobacteriumsp. NRC‐1, cyanobacteria such asAphanothece halophytica, and the green algaDunaliella salina. Multicellular halophilic eukaryotic organisms include brine shrimp and the larvae of brine flies. Halophilic organisms either accumulate internal organic compatible solutes to balance the osmotic stress of the environment or produce acidic proteins to increase solvation and improve function in high salinity.Key Concepts:Halophiles are salt‐loving organisms that inhabit saline and hypersaline environments and include prokaryotic (archaeal and bacterial) and eukaryotic organisms.Many halophiles accumulate compatible solutes in cells to balance the osmotic stress in their environment.Some halophiles produce acidic proteins that are able to function in high salinity by increasing solvation and preventing aggregation, precipitation and denaturation.