A novel halophilic archaeon, designated strain 2b_61_3T, was isolated from a solar saltern in Indonesia. Cells of the strain were Gram-stain-negative, motile, pleomorphic rods that formed orange–red-pigmented colonies on solid medium. The isolate grew optimally at 42-44 °C, pH 6.5–7.0, and with 2.6 M NaCl, and MgCl2 was required for growth. Strain 2b_61_3T had two differential 16S rRNA genes (rrnA and rrnB), and phylogenetic analysis revealed that the strain belonged to the genus Haloarchaeobius. The rrnA and rrnB sequence similarities between strain 2b_61_3T and species of the genus Haloarchaeobius were 98.4–99.2 % and 98.5–98.8 %, respectively. The findings from the 16S rRNA gene analysis were supported by sequence analysis of rpoB′, the B′ subunit of RNA polymerase. On the basis of the phenotypic characteristics and phylogenetic analyses, as well as DNA–DNA hybridization experiments with Haloarchaeobius iranensis NBRC 110930T, strain 2b_61_3T represents a novel species of the genus Haloarchaeobius, for which the name Haloarchaeobius baliensis sp. nov. is proposed. The type strain is 2b_61_3T ( = NBRC 110517T = InaCC Ar2T).
Two novel cell-wall-less, acidophilic, mesophilic, organotrophic and facultatively anaerobic archaeal strains were isolated from acidic streamers formed on the surfaces of copper-ore-containing sulfidic deposits in south-west Spain and North Wales, UK. Cells of the strains varied from 0.1 to 2 μm in size and were pleomorphic, with a tendency to form filamentous structures. The optimal pH and temperature for growth for both strains were 1.0–1.2 and 37–40 °C, with the optimal substrates for growth being beef extract (3 g l− 1) for strain S5T and beef extract with tryptone (3 and 1 g l− 1, respectively) for strain PM4. The lipid composition was dominated by intact polar lipids consisting of a glycerol dibiphytanyl glycerol tetraether (GDGT) core attached to predominantly glycosidic polar headgroups. In addition, free GDGT and small relative amounts of intact and core diether lipids were present. Strains S5T and PM4 possessed mainly menaquinones with minor fractions of thermoplasmaquinones. The DNA G+C content was 37.3 mol% in strain S5T and 37.16 mol% for strain PM4. A similarity matrix of 16S rRNA gene sequences (identical for both strains) showed their affiliation to the order Thermoplasmatales, with 73.9–86.3 % identity with sequences from members of the order with validly published names. The average nucleotide identity between genomes of the strains determined in silico was 98.75 %, suggesting, together with the 16S rRNA gene-based phylogenetic analysis, that the strains belong to the same species. A novel family, Cuniculiplasmataceae fam. nov., genus Cuniculiplasma gen. nov. and species Cuniculiplasma divulgatum sp. nov. are proposed based on the phylogenetic, chemotaxonomic analyses and physiological properties of the two isolates, S5T and PM4 ( = JCM 30641 = VKM B-2940). The type strain of Cuniculiplasma divulgatum is S5T ( = JCM 30642T = VKM B-2941T).
Two extremely halophilic archaea, strains Cb34T and C170, belonging to the genus Halorubrum, were isolated from the brine of the hypersaline lake Aran-Bidgol in Iran. Cells of the two strains were motile, pleomorphic rods, stained Gram-variable and produced red-pigmented colonies. Strains Cb34T and C170 required 25 % (w/v) salts, pH 7.0 and 37 °C for optimal growth under aerobic conditions; 0.3 M Mg2+ was required. Cells of both isolates were lysed in distilled water and hypotonic treatment with < 10 % NaCl provoked cell lysis. Phylogenetic analysis based on 16S rRNA gene sequence similarities showed that these two strains were closely related to Halorubrum cibi B31T (98.8 %) and other members of the genus Halorubrum. In addition, studies based on the rpoB′ gene revealed that strains Cb34T and C170 are placed among the species of Halorubrum and are closely related to Halorubrum cibi B31T, with rpoB′ gene sequence similarity less than or equal to 95.7 %. The polar lipid patterns of both strains consisted of phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate and sulfated mannosyl glucosyl diether. The DNA G+C content was 62.1–62.4 mol%. DNA–DNA hybridization studies confirmed that strains Cb34T and C170 constitute a distinct species. Data obtained in this study show that the two strains represent a novel species, for which the name Halorubrum halodurans sp. nov. is proposed. The type strain is Cb34T ( = CECT 8745T = IBRC-M 10233T).