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| Natronomonas | |
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| Genus: | Natronomonas |
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| Natronomonas pharaonis (Soliman & Truper 1983) Kamekura et al. 1997 | |
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Natronomonas (common abbreviation Nmn.) is a genus of the Halobacteriaceae. [1]
Natronomonas pharaonis is an aerobic, extremely haloalkaliphilic archaeon that grows optimally in 3.5M sodium chloride and at pH 8.5, but is sensitive to high magnesium concentrations.
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) [2] and National Center for Biotechnology Information (NCBI). [1]
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The genome of Natronomonas pharaonis consists of three circular replicons, the chromosome which is 2,595,221 bp in length, a typical haloarchaeal 131-kb plasmid, and a unique multicopy 23-kb plasmid. Its chromosome has a high G + C content (63.4%). Also, a high proportion of acidic amino acids (average 19.3%) is found in the proteins of N. pharaonis which results in low isoelectric points (average pI 4.6). This is considered to be one of the adaptive features of haloarchaea, which are known to apply the salt-in strategy (high internal salt concentrations) in order to survive in their hypersaline environment (Falb et al.). Further, it is noteworthy that because the archaeon lacks the genetic encoding for key enzymes for glycolytic pathways, it is not capable of sugar utilization.
Natronomonas, like the other members of Halobacteriaceae, has a distinct physiological characteristics because it not only requires high NaCl concentrations but also high pH and low Mg2+ concentrations for growth. It usually utilizes amino acids as the carbon source, but the series of studies discovered that the archaeon has a high degree of nutritional self-sufficiency. Also, in contrast to other alkaliphiles, which use sodium Na+ instead of protons H+ as coupling ion between respiratory chain and ATP synthase, Natronomonas uses protons as coupling ion.
The archaeon grows under highly alkaline conditions of pH around 11, which causes reduced levels of ammonia in addition to low availability of metal ions. The genome analysis shows that, in its nitrogen metabolism process, the archaeon has three mechanisms that supply ammonia, which is then assimilated into glutamate: direct uptake of ammonia, uptake of nitrate and subsequent reduction to ammonia, and uptake of urea which is split by urease to release ammonia. The green arrows in the figure represent the transporters for exogenous nitrogen source ammonia (AmtB), nitrate (NarK), and urea (UrtA-E), and the blue arrows represent the enzymes for reduction of nitrate (NarB + Nir A) and hydrolysis of urea (UreA-G). Other abbreviations: GlnA + GltB = glutamate; 2-OG = oxoglutarate; fdx = ferredoxin.
It is probable that Natronomonas uses ferredoxin and not NADH as the electron donor for all three reductive conversions. This is evident from the occurrence of conserved ferredoxin-binding residues within the N. pharaonis NirA protein and ferredoxin dependence of nitrate and nitrite reductases in the halophile Haloferax mediterranei .
Strains of N. pharaonis were first isolated from highly saline soda lakes in Egypt and Kenya, which show pH values around 11.
Halobacterium is a genus in the family Halobacteriaceae.
Halobacteriaceae is a family in the order Halobacteriales and the domain Archaea. Halobacteriaceae represent a large part of halophilic Archaea, along with members in two other methanogenic families, Methanosarcinaceae and Methanocalculaceae. The family consists of many diverse genera that can survive extreme environmental niches. Most commonly, Halobacteriaceae are found in hypersaline lakes and can even tolerate sites polluted by heavy metals. They include neutrophiles, acidophiles, alkaliphiles, and there have even been psychrotolerant species discovered. Some members have been known to live aerobically, as well as anaerobically, and they come in many different morphologies. These diverse morphologies include rods in genus Halobacterium, cocci in Halococcus, flattened discs or cups in Haloferax, and other shapes ranging from flattened triangles in Haloarcula to squares in Haloquadratum, and Natronorubrum. Most species of Halobacteriaceae are best known for their high salt tolerance and red-pink pigmented members, but there are also non-pigmented species and those that require moderate salt conditions. Some species of Halobacteriaceae have been shown to exhibit phosphorus solubilizing activities that contribute to phosphorus cycling in hypersaline environments. Techniques such as 16S rRNA analysis and DNA-DNA hybridization have been major contributors to taxonomic classification in Halobacteriaceae, partly due to the difficulty in culturing halophilic Archaea.
Halalkalicoccus is a genus of the Halobacteriaceae.
Halobaculum is a genus of the Halorubraceae.
Halobiforma is a genus of halophilic archaea of the family Natrialbaceae.
In taxonomy, Haloferax is a genus of the Haloferacaceae.
In taxonomy, Halogeometricum is a genus of the Haloferacaceae.
Halomicrobium is a genus of the Haloarculaceae.
Halopiger is a genus of archaeans in the family Natrialbaceae that have high tolerance to salinity.
Halorhabdus is a genus of halophilic archaea in the Haloarculaceae. With an extremely high salinity optimum of 27% NaCl, Halorhabdus has one of the highest reported salinity optima of any living organism.
Halorubrum is a genus in the family Halorubraceae. Halorubrum species are usually halophilic and can be found in waters with high salt concentration such as the Dead Sea or Lake Zabuye.
Haloterrigena is a genus of the Natrialbaceae.
In taxonomy, Halovivax is a genus of the Natrialbaceae. Some species of Halovivax are halophiles and have been found in Iran's Aran-Bidgol hypersaline lake.
In taxonomy, Natrialba is a genus of the Natrialbaceae. The genus consists of many diverse species that can survive extreme environmental niches, especially they are capable to live in the waters saturated or nearly saturated with salt (halophiles). They have certain adaptations to live within their salty environments. For example, their cellular machinery is adapted to high salt concentrations by having charged amino acids on their surfaces, allowing the cell to keep its water molecules around these components. The osmotic pressure and these amino acids help to control the amount of salt within the cell.
Natrinema is a genus of the Natrialbaceae.
In taxonomy, Natronobacterium is a genus of the Natrialbaceae. A member of the domain Archaea, it is both an extreme halophile and alkaliphile, thriving at an optimum saline concentration of 20% and optimum pH of 10.
In taxonomy, Natronococcus is a genus of the Natrialbaceae.
Natronorubrum is a genus in the family Halobacteriaceae.
In taxonomy, Methanofollis is a genus of the Methanomicrobiaceae.
Halorubraceae is a family of halophilic, chemoorganotrophic or heterotrophic archaea within the order Haloferacales. The type genus of this family is Halorubrum. Its biochemical characteristics are the same as the order Haloferacales.