Haloferax larsenii
| Haloferax larsenii | |
|---|---|
| Scientific classification | |
| Domain: | Archaea |
| Phylum: | Euryarcheota |
| Class: | Halobacteria |
| Order: | Halobacteriales |
| Family: | Halobacteriaceae |
| Genus: | Haloferax |
| Species: | H. larsenii |
| Binomial name | |
| Haloferax larsenii Xue-Wei Xu et al. 2007 | |
Haloferax larsenii is a Gram-negative, aerobic, neutrophilic, extremely halophilic archaea. It was named in honor of Professor Helge Larsen, who pioneered research on halophiles.[1]
Discovery
Haloferax larsenii was isolated from a solar saltern in the Zhoushan archipelago, Zhejiang Province, China. The researchers who discovered this species isolated three strains of Hfx. larsenii. When this species was discovered, the genus Haloferax comprised Haloferax volcanii, Hfx. mediterranei, Hfx. denitrificans, Hfx. gibbonsii, Hfx. alexandrinus, Hfx. lucentense, and Hfx. sulfurifontis.[1] Since this time, Hfx. prahovense, Hfx. elongans, and Hfx. mucosum have been discovered, which totals to eleven species in the genus.[2]
Diversity
Like most species in Haloferax, Hfx. larsenii was isolated from an extremely salty environment consisting of a mixture of mud and brine. Through isolation and characterization techniques, three strains were identified by Xu et al. (2007), each having 99.8-100% similarity as shown by 16S rRNA gene sequences. This cluster of Haloferax larsenii strains are distinguished from other Haloferax species with 96.4-97.4% similarity to the closest known Haloferax species. They also have a 92.3-92.5% similarity with its most recent common ancestor, Halogeometricum borinquense, outside of Haloferax. Phylogenetic, phenotypic, and chemotaxonomic data show the novelty of the strain identified as ZJ206T as part of the genus Haloferax and given the species name Hfx. larsenii.[1]
Phylogeny[3]
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Characteristics
Cells of Haloferax larsenii are extremely pleomorphic and irregularly shaped with a diameter of 0.8-1.5 µm. Motility of cells has been noted, but flagella have not been observed by electron microscopy. The major polar lipids are the C20C20 derivatives of phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, diglycosyl glycerol diether and sulfated diglycosyl diether. The DNA G+C content of DNA of the ZJ206T strain is 62.2±0.8 mol% as determined by thermal denaturation.
When grown on complex agar medium, colonies appeared orange-red, smooth, circular, elevated, and 1–2 mm in diameter. Colonies can grow with NaCl concentrations of 1.0-4.8 M, with optimum growth between 2.2-3.4 M. However, saturated NaCl inhibits growth in liquid medium. The optimum pH for growth is 6.5-7.0 and the optimum temperature for growth is 42-45oC. Anaerobic growth occurs on nitrate with the production of gas; nitrate is reduced to nitrite.
Glucose, glycerol, mannose, starch, maltose, sucrose, glutamate, alanine, ornithine, fumarate, malate, pyruvate, succinate, and lactate substrates support growth. Growth is not sustained on arabinose, lactose, mannitol, rhamnose, sorbitol, galactose, ribose, xylose, arginine, lysine, aspartate, glycine, acetate, propionate, and citrate.
Sensitivity to novobiocin, bacitracin, anisomycin, aphidicolin, and rifampicin have been observed. However, no sensitivity has been shown to ampicillin, penicillin, chloramphenicol, erythromycin, neomycin, nalidixic acid, nystatin, tetracycline, streptomycin, or kanamycin.
Furthermore, Hfx. larsenii was shown to form indole, hydrolyze gelatin, starch, and Tweens 40 and 80, produce acid from glycerol, maltose, glucose, fructose, and sucrose, and form H2S from thiosulfate.[1]
References
- 1 2 3 4 Xu, Xue-Wei; et al. (2007). "Haloferax larsenii sp. nov., an extremely halophilic archaeon from a solar saltern". International Journal of Systematic and Evolutionary Microbiology 57.4: 717–720. doi:10.1099/ijs.0.64573-0.
- ↑ Allen, Michelle A.; et al. (2008). "Haloferax elongans sp. nov. and Haloferax mucosum sp. nov., isolated from microbial mats from Hamelin Pool, Shark Bay, Australia". International Journal of Systematic and Evolutionary Microbiology 58.4: 798–802. doi:10.1099/ijs.0.65360-0. PMID 18398172.
- ↑ Tekin, Ebru; Ateş, Mustafa; Kahraman, Özge (2012). "Poly-3-hydroxybutyrate-producing extreme halophilic archaeon: Haloferax sp. MA10 isolated from Çamaltı Saltern, İzmir". Turk J Biol 36: 303–312.