A Gram-stain-negative, cream‐pigmented, motile, extremely halophilic archaeon, designated strain IC38T, was isolated from a saline mud sample taken from a hypersaline lake, Aran-Bidgol, in Iran. The strain required at least 2.5 M NaCl for growth. However, MgCl2 was not required. Optimal growth occurred with 4.3 M NaCl and 0.2 M MgCl2. The optimum pH and temperature for growth were pH 7.0 and 35 °C, respectively, and strain IC38T was able to grow over a pH range of 6.5–9.0, and a temperature range of 25–45 °C. Analysis of the 16S rRNA gene sequence revealed that strain IC38T clustered with the two species of the genus Halovivax , Halovivax asiaticus EJ-46T and Halovivax ruber XH-70T, with sequence similarities of 96.4 % and 96.1 %, respectively. The similarities between the rpoB′ gene of the novel strain and Halovivax asiaticus and Halovivax ruber were 90.7 % and 90.3 %, respectively. The polar lipid pattern of strain IC38T consisted of phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester. Three unidentified glycolipids and two minor phospholipids were also observed. The DNA G+C content of strain IC38T was 62.6 mol%. On the basis of the phylogenetic analysis, as well as the biochemical and physiological characteristics, the new isolate is suggested to be a representative of a novel species of the genus Halovivax , for which the name Halovivax limisalsi sp. nov. is proposed. The type strain of Halovivax limisalsi is IC38T ( = IBRC-M 10022T = KCTC 4051T).
A novel methanogenic archaeon, strain MC-15T, was isolated from a floating biofilm on a sulphurous subsurface lake in Movile Cave (Mangalia, Romania). Cells were non-motile sarcina-like cocci with a diameter of 2–4 µm, occurring in aggregates. The strain was able to grow autotrophically on H2/CO2. Additionally, acetate, methanol, monomethylamine, dimethylamine and trimethylamine were utilized, but not formate or dimethyl sulfide. Trypticase peptone and yeast extract were not required for growth. Optimal growth was observed at 33 °C, pH 6.5 and a salt concentration of 0.05 M NaCl. The predominant membrane lipids of MC-15T were archaeol and hydroxyarchaeol phosphatidylethanolamine, phosphatidylglycerol, and phosphatidylinositol as well as hydroxyarchaeol phosphatidylserine and archaeol glycosaminyl phosphatidylinositol. The closely related species, Methanosarcina vacuolata and Methanosarcina horonobensis, had a similar composition of major membrane lipids to strain MC-15T. The 16S rRNA gene sequence of strain MC-15T was similar to those of Methanosarcina vacuolata DSM 1232T (sequence similarity 99.3 %), Methanosarcina horonobensis HB-1T (98.8 %), Methanosarcina barkeri DSM 800T (98.7 %) and Methanosarcina siciliae T4/MT (98.4 %). DNA–DNA hybridization revealed 43.3 % relatedness between strain MC-15T and Methanosarcina vacuolata DSM 1232T. The G+C content of the genomic DNA was 39.0 mol%. Based on physiological, phenotypic and genotypic differences, strain MC-15T represents a novel species of the genus Methanosarcina , for which the name Methanosarcina spelaei sp. nov. is proposed. The type strain is MC-15T ( = DSM 26047T = JCM 18469T).