In comparison with the thermophilic and the alkaliphilic extremophiles, halophilic microorganisms have as yet found
relatively few biotechnological applications. Halophiles are involved in centuries-old processes such as the
manufacturing of solar salt from seawater and the production of traditional fermented foods. Two biotechnological
processes involving halophiles are highly successful: the production of
β
-carotene by the green alga
Dunaliella
and
the production of ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid), used as a stabilizer for enzymes
and now also applied in cosmetic products, from moderately halophilic bacteria. The potential use of
bacteriorhodopsin, the retinal protein proton pump of
Halobacterium
, in optoelectronic devices and photochemical
processes is being explored, and may well lead to commercial applications in the near future. Demand for salt-tolerant
enzymes in current manufacturing or related processes is limited. Other possible uses of halophilic microorganisms
such as treatment of saline and hypersaline wastewaters, and the production of exopolysaccharides, poly-
β
-
hydroxyalkanoate bioplastics and biofuel are being investigated, but no large-scale applications have yet been
reported.