Haloferax mediterranei
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| Haloferax mediterranei | |
|---|---|
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| SEM image of Haloferax mediterranei. | |
Scientific classification  | |
| Domain: | Archaea |
| Kingdom: | Methanobacteriati |
| Phylum: | Methanobacteriota |
| Class: | Halobacteria |
| Order: | Haloferacales |
| Family: | Haloferacaceae |
| Genus: | Haloferax |
| Species: | H. mediterranei |
| Binomial name | |
| Haloferax mediterranei (Rodriguez-Valera et al. 1983) Torreblanca et al. 1987[1] | |
| Synonyms | |
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Haloferax mediterranei is a species of archaea in the family Haloferacaceae.[1]
Haloferax mediterranei was discovered in 1983 in marine salterns in the village of Santa Pola, Spain.[2] The species was initially named Halobacterium mediterranei, then renamed Haloferax mediterranei in 1986.[3] Haloferax mediterranei is the fastest-growing known member of the Halobacteriales under optimal laboratory conditions, but it is relatively rare in the environment.[4] The full genome of H. mediterranei was sequenced in 2012.[5]
Metabolism and Growth Conditions
Haloferax mediterranei is the fastest-growing archaeon in the Halobacteriales family,[4] with generation times as low as 1.2 hours reported under optimal laboratory growth conditions.[6] Haloferax mediterranei is able to use a variety of compounds as carbon and energy sources,[7] and can accumulate materials to serve as a source of carbon and energy, as well as use organic and inorganic nitrogen sources.[4] H. mediterranei is an extremely versatile microorganism that can anaerobically or aerobically, tolerate a wide range of salinities (between 10% and 32.5%), a wide range of pH values (between 5.75 and 8.75) and a wide range of temperatures (between 18 and 55 °C).[7][6][4] It can also tolerate a variety of high metal concentrations, such as nickel, lithium, cobalt and arsenic, which are toxic to most organisms.[6]
Morphology and Cell Division
Haloferax mediterranei is an extremely pleomorphic organism, cells are usually flat disks.[4] Like Haloferax volcanii, it performs cell division through the formation of an FtsZ ring.[8]
Biofilm and Exopolysaccharide formation
Haloferax mediterranei produces a mucous exopolysaccharide matrix that accumulates as a top layer in liquid medium.[9] This is a widespread strategy in the microbial world that helps biofilms adhere to surfaces, as well as protects cells from pH and temperature variations and radiation.[10] These exopolysaccharides have been studied as potential emulsifiers for industry.[9] The unshaken biofilms of H. mediterranei in liquid cultures rapidly rearrange into a honeycomb formation pattern upon exposure to air, a phenomenon that has yet to be fully elucidated.[11]
PHA and PHB synthesis
H. mediterranei, when grown under phosphate limitation,[12] produces polyhydroxyalkanoates, a type of biodegradable thermoplastic currently commercially produced using bacteria.[13] It has been suggested that H. mediterranei is a good candidate for industrial production of biodegradable thermoplastics due to its fast growth, low contamination rates and ease of lysis.[14] Deleting the genes responsible for exopolysaccharide synthesis results in a 20% increase in the amount of PHAs in the cell.[13] Increasing the salt concentration of the media also increased the concentration of PHAs produced.[15]