Halobacterium salinarum
Halobacterium is an extremely halophilic marine gram-negative obligate aerobic archaeon. Despite its name, this microorganisms is not a bacterium, but rather a member of the Domain Archaea. It is found in salted fish, hides, hypersaline lakes, and salterns. Salterns are enclosed basins filled with seawater that are left to evaporate, yielding solar sea salt. As these salterns reach the minimum salinity limits for extreme halophiles, their waters become purple or reddish color due to the algal bloom of halophilic Archaea. H. salinarum has also been found in high-salt food such as salt pork, marine fish, and sausages.
To survive in extremely salty environments, this archaeon—as with other halophilic Archaean species—utilizes compatible solutes (in particular potassium chloride) that acts as a sort of antifreeze/coolant to keep the cell metabolism functioning.
H. salinarum is an obligate aerobe. It reproduces by binary fission. It does not form spores. Most are not motile.
Halobacterium salinarum is responsible for the bright pink or red appearance of the Dead Sea and other bodies of salt water.
Halobacteria are single-celled, rod-shaped microorganisms that are among the most ancient forms of life and appeared on earth billions of years ago. Halobacteria are archaea that grow optimally in extremely high saline environments (up to 5.5 M NaCl). Their natural habitats are salt evaporation ponds and natural salt lakes and other environments where the salt concentration comes close to saturation. Occasionally they are isolated from hides and from the surfaces of heavily salted foods.
Halobacterium sp. NRC-1 is as easy to culture as E. coli and serves as an excellent model system for archaeal genetics and functional genomics.
Whole proteome comparisons show the definite archaeal nature of this halophile with additional similarities to the Gram-positive Bacillus subtilis and other bacteria.
Whole genome sequences are available for two strains of H. salinarum, NRC-1 and R1.
References
- Ng, Wailap Victor; et al. (2000). "Genome sequence of Halobacterium species NRC-1". PNAS 97 (22): 12176–12181. http://www.pnas.org/content/97/22/12176.abstract.
