A novel halophilic archaeon, strain MH1-52-1T, was isolated from solar salt imported from Australia. Cells were pleomorphic, non-motile and Gram-negative. Strain MH1-52-1T required at least 3.0 M NaCl and 1 mM Mg2+ for growth. Strain MH1-52-1T was able to grow at pH 4.0–6.0 (optimum, pH 4.4–4.5) and 15–45 °C (optimum, 37 °C). The diether phospholipids phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester, derived from both C20C20 and C20C25 archaeol, were present. Four unidentified glycolipids were also detected. The 16S rRNA gene sequence showed the highest similarity to that of Halobacterium noricense A1T (91.7 %); there were lower levels of similarity to other members of the family Halobacteriaceae. The G+C content of its DNA was 61.4 mol%. Based on our phenotypic, genotypic and phylogenetic analyses, it is proposed that the isolate should be classified as a representative of a new genus and species, for which the name Halarchaeum acidiphilum gen. nov., sp. nov. is proposed. The type strain of Halarchaeum acidiphilum is MH1-52-1T (=JCM 16109T =DSM 22442T =CECT 7534T).
Strain YSM-123T was isolated from commercial salt made from Japanese seawater in Niigata prefecture. Optimal NaCl and Mg2+ concentrations for growth were 4.0–4.5 M and 5 mM, respectively. The isolate was a mesophilic and slightly alkaliphilic haloarchaeon, whose optimal growth temperature and pH were 37 °C and pH 8.0–9.0. Phylogenetic analysis based on 16S rRNA gene sequence analysis suggested that strain YSM-123T is a member of the phylogenetic group defined by the family Halobacteriaceae, but there were low similarities to type strains of other genera of this family (≤90 %); for example, Halococcus (similarity <89 %), Halostagnicola (<89 %), Natronolimnobius (<89 %), Halobiforma (<90 %), Haloterrigena (<90 %), Halovivax (<90 %), Natrialba (<90 %), Natronobacterium (<90 %) and Natronococcus (<90 %). The G+C content of the DNA was 63 mol%. Polar lipid analysis revealed the presence of phosphatidylglycerol, phosphatidylglycerophosphate methyl ester, disulfated diglycosyl diether and an unknown glycolipid. On the basis of the data presented, we propose that strain YSM-123T should be placed in a new genus and species, Natronoarchaeum mannanilyticum gen. nov., sp. nov. The type strain of Natronoarchaeum mannanilyticum is strain YSM-123T (=JCM 16328T =CECT 7565T).
A mesophilic, hydrogenotrophic methanogen, designated strain Ki8-1T, was isolated from soil. Cells were strictly anaerobic, Gram-stain-negative, non-sporulating, motile by means of a single flagellum or tufted flagella, and curved or wavy rod-shaped (11–25 μm long). The temperature and pH for optimum growth were 30 °C and 7.5. The strain grew best in basal medium without the addition of NaCl. Methane was produced from H2 and formate. Acetate or yeast extract was required for growth. The G+C content of the genomic DNA of strain Ki8-1T was 45.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain Ki8-1T was a member of the genus Methanospirillum and showed 95.1 % sequence similarity to Methanospirillum hungatei NBRC 100397T. On the basis of its phenotypic characteristics and phylogenetic position, strain Ki8-1T is considered to represent a novel species of the genus Methanospirillum, for which the name Methanospirillum lacunae sp. nov. is proposed. The type strain is Ki8-1T (NBRC 104920T =JCM 16384T =DSM 22751T). Emended descriptions of the genus Methanospirillum and of Methanospirillum hungatei are also provided.
Two halophilic archaea, strains RO1-4T and RO1-64, were isolated from a marine solar saltern in Jiangsu, China. Cells of the two strains were pleomorphic, motile, and stained Gram-negative. Colonies were red-pigmented. Strains RO1-4T and RO1-64 were able to grow at 25–55 °C (optimum 40–42 °C), at 2.1–5.1 M NaCl (optimum 3.9 M NaCl), at 0.05–0.7 M MgCl2 (optimum 0.3 M MgCl2) and at pH 6.0–8.5 (optimum pH 7.0). Cells lyse in distilled water and the minimal NaCl concentration to prevent cell lysis is 12 % (w/v). On the basis of 16S rRNA gene sequence analysis, strains RO1-4T and RO1-64 were closely related to Halogeometricum borinquense PR3T (98.0 and 98.2 % similarity, respectively) and Halosarcina pallida BZ256T (97.8 and 97.9 %). The major polar lipids of the two strains were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and two glycolipids (S-DGD-1 and DGD-1). The DNA G+C contents of strains RO1-4T and RO1-64 are 64.9 and 62.4 mol%, respectively. The DNA–DNA hybridization value between strains RO1-4T and RO1-64 was 83.0 % and both strains showed low DNA–DNA relatedness with Halogeometricum borinquense PR3T (42.5 and 50.1 % relatedness, respectively) and Halosarcina pallida BZ256T (37.6 and 42.1 % relatedness). It was concluded that strains RO1-4T and RO1-64 represent a novel species of the genus Halogeometricum, for which the name Halogeometricum rufum sp. nov. is proposed. The type strain is RO1-4T (=CGMCC 1.7736T =JCM 15770T).