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Two extremely halophilic archaea, strains RO2-11(T) and HO2-1, were isolated from two Chinese marine solar salterns, Rudong solar saltern and Haimen solar saltern, respectively. Cells of the two strains were polymorphic and Gram-stain-negative; colonies were red-pigmented. The two strains grew at NaCl concentrations of 2.6-4.3 M (optimum 3.9 M) and required at least 0.1 M Mg2+ for growth. They were able to grow over a pH range of 6.0-8.0 and a temperature range of 20-50 degrees C, with optimal pH of 7.5 and optimal temperature of 37 degrees C. The major polar lipids of strain RO2-11(T) and strain HO2-1 were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and three glycolipids, two of them chromatographically identical to S-DGD-1 and DGD-1, the third unidentified. The 16S rRNA gene sequence similarity of strain RO2-11(T) and strain HO2-1 was 99.3 % and highest sequence similarity with the closest relative (Haloferax larsenii) was 91.4 %. Based on the data obtained, the two isolates could not be classified in any recognized genus of the family Halobacteriaceae. Strain RO2-11(T) and strain HO2-1 are thus considered to represent a novel species of a new genus within the family Halobacteriaceae, for which the name Halogranum rubrum gen. nov., sp. nov. is proposed. The type strain is RO2-11(T) (=CGMCC 1.7738(T) =JCM 15772(T)).

Extremely halophilic archaea were cultivated from smooth and pustular microbial mats collected from Hamelin Pool, Shark Bay, Western Australia. On the basis of morphology, two phenotypes were present and 16S rRNA gene sequence analysis indicated that all strains were most closely related to members of the genus Haloferax (98.1-99.4 % similarity). One representative strain from each phenotype was selected for further taxonomic characterization. Strain SA5T, isolated from the smooth mat, formed small ( approximately 1 mm diameter), red, translucent colonies on agar medium and strain PA12T, isolated from the pustular mat, formed large (3-5 mm diameter), pink, mucoid, domed colonies. Both strains grew in media with 1.7-5.1 M NaCl, required at least 0.2 M Mg2+ for growth and had pH optima of 7.4. The 16S rRNA gene similarity between strains SA5T and PA12T was 97.1 %. Physiological properties, G+C content and polar lipid composition supported placement of both strains in the genus Haloferax. Phenotypic analysis indicated that the two strains were distinct from each other and from all other members of the genus. This was confirmed by the low DNA-DNA relatedness between strains SA5T and PA12T (18-30 %) and between both strains and all other recognized Haloferax species. Two novel species of the genus Haloferax are proposed to accommodate these novel isolates, Haloferax elongans sp. nov. (type strain SA5T=JCM 14791T=ATCC BAA-1513T=UNSW 104100T) and Haloferax mucosum sp. nov. (type strain PA12T=JCM 14792T=ATCC BAA-1512T=UNSW 104200T).

Three strains of Gram-negative, aerobic, neutrophilic, extremely halophilic archaea, designated ZJ206(T), ZJ203 and ZJ204, were isolated from a solar saltern in Zhe-Jiang Province, China. Phenotypically and on the basis of 16S rRNA gene sequences, the strains were very similar. Comparative 16S rRNA gene analysis revealed 96.4-97.4 % sequence similarity to members of the genus Haloferax. The major polar lipids were C(20)C(20) derivatives of phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, diglycosyl glycerol diether and sulfated diglycosyl diether. The DNA G+C content of strain ZJ206(T) was 62.2 mol%. The results of DNA-DNA hybridizations and physiological and biochemical tests allowed genotypic and phenotypic differentiation of the isolates from closely related species. Therefore the isolates should be classified as members of a novel species, for which the name Haloferax larsenii sp. nov. is proposed. The type strain is ZJ206(T) (=CGMCC 1.5347(T)=JCM 13917(T)).

A novel halophilic archaeon, strain TL6T, was isolated from Telega Lake, a hypersaline environment in Prahova county, Romania. Strain TL6T was able to grow in media with a salt concentration of between 2.5 and 5.2 M, with optimum growth at a concentration of 3.5 M. The novel strain was able to grow at concentrations of 1 M MgCl2 or less, with an optimum of 0.4 M Mg2+. Growth of the novel strain occurred between pH 6.0 and 8.5, with an optimum of pH 7.0-7.5. The G+C content of the total DNA was 63.7 mol%. The 16S rRNA gene sequence of the novel strain was most closely related to species of the genus Haloferax (97.3-99.3 % sequence similarity). The lipid profile of the novel strain corresponded to that of other species belonging to the genus Haloferax. A comparative analysis of the phenotypic properties and DNA-DNA hybridization between the novel strain and other species of the genus Haloferax strongly supported the conclusion that strain TL6T represents a novel species within this genus, for which the name Haloferax prahovense sp. nov., is proposed. The type strain is TL6T (=JCM 13924T=DSM 18310T).

A pleomorphic, extremely halophilic archaeon (strain M6(T)) was isolated from a sulfide- and sulfur-rich spring in south-western Oklahoma (USA). It formed small (0.8-1.0 mm), salmon pink, elevated colonies on agar medium. The strain grew in a wide range of NaCl concentrations (6 % to saturation) and required at least 1 mM Mg(2+) for growth. Strain M6(T) was able to reduce sulfur to sulfide anaerobically. 16S rRNA gene sequence analysis indicated that strain M6(T) belongs to the family Halobacteriaceae, genus Haloferax; it showed 96.7-98.0 % similarity to other members of the genus with validly published names and 89 % similarity to Halogeometricum borinquense, its closest relative outside the genus Haloferax. Polar lipid analysis and DNA G+C content further supported placement of strain M6(T) in the genus Haloferax. DNA-DNA hybridization values, as well as biochemical and physiological characterization, allowed strain M6(T) to be differentiated from other members of the genus Haloferax. A novel species, Haloferax sulfurifontis sp. nov., is therefore proposed to accommodate the strain. The type strain is M6(T) (=JCM 12327(T)=CCM 7217(T)=DSM 16227(T)=CIP 108334(T)).