''Haloferax larsenii'' is a

gram-negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...

aerobic Aerobic means "requiring air," in which "air" usually means oxygen. Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics, a form of aerobic exercise * Aerobic respiration, the aerobic process of cellu ...

, neutrophilic, extremely halophilic

archaeon Archaea ( ) is a domain of organisms. Traditionally, Archaea only included its prokaryotic members, but this has since been found to be paraphyletic, as eukaryotes are known to have evolved from archaea. Even though the domain Archaea cladis ...

. It was named in honor of Professor

Helge Larsen Helge Larsen (25 April 1915 – 24 January 2000) was a Danish politician. He was a member of the Danish Social Liberal Party and served as the minister of education between 1968 and 1971. Early life and education Larsen was born on 25 April 1 ...

, who pioneered research on

halophiles A halophile (from the Greek word for 'salt-loving') is an extremophile that thrives in high salt concentrations. In chemical terms, halophile refers to a Lewis acidic species that has some ability to extract halides from other chemical species. ...

Discovery

''Haloferax larsenii'' was isolated from a solar saltern in the

Zhoushan archipelago Zhoushan is an urbanized archipelago with the administrative status of a prefecture-level city in the eastern Chinese province of Zhejiang. It consists of an archipelago of islands at the southern mouth of Hangzhou Bay off the mainland c ...

Zhejiang Province ) , translit_lang1_type2 = , translit_lang1_info2 = ( Hangzhounese) ( Ningbonese) (Wenzhounese) , image_skyline = 玉甑峰全貌 - panoramio.jpg , image_caption = View of the Yandang Mountains , image_map = Zhejiang i ...

, China. The researchers who discovered this species isolated three strains of ''H. larsenii''. When this species was discovered, the genus ''Haloferax'' comprised ''

Haloferax volcanii ''Haloferax volcanii'' is a species of archaean in the genus '' Haloferax'' in the Archaea. Description and significance ''Haloferax volcanii'' is a halophilic mesophile archaeon that can be isolated from hypersaline environments such as: the ...

'', ''H. mediterranei'', ''H. denitrificans'', ''H. gibbonsii'', ''H. alexandrinus'', ''H. lucentense'', and ''H. sulfurifontis''. Since this time, ''H. prahovense'', ''H. elongans'', and ''H. mucosum'' have been discovered, which totals to 11 species in the genus.

Diversity

Like most species in ''

Haloferax ''Haloferax'' (common abbreviation: ''Hfx.'') is a genus of halobacteria in the order Haloferacaceae. Genetic exchange Cells of ''H. mediterranei'' and cells of the related species '' H. volcanii'' can undergo a process of genetic exchange betw ...

'', ''H. larsenii'' was isolated from an extremely salty environment consisting of a mixture of mud and brine.

Phylogenetic position

The species has been placed in a

phylogeny A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...

Characteristics

Cells of ''H. 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 An electron microscope is a microscope that uses a beam of electrons as a source of illumination. It uses electron optics that are analogous to the glass lenses of an optical light microscope to control the electron beam, for instance focusing i ...

. 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 ZJ206^T 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 and 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 42-45 °C. 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, ''H. 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.

References

External links

Type strain of ''Haloferax larsenii'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q20081188 Halobacteria Archaea described in 2007