Two extremely halophilic archaea, strains MGY-184T and MGY-205, were isolated from sea salt produced in Japan and rock salt imported from Bolivia, respectively. Both strains were pleomorphic, non-motile, Gram-negative and required more than 5 % (w/v) NaCl for growth, with optimum at 9–12 %, in the presence of 2 % (w/v) MgCl2 . 6H2O. In the presence of 18 % (w/v) MgCl2 . 6H2O, however, both strains showed growth even at 1.0 % (w/v) NaCl. Both strains possessed two 16S rRNA genes (rrnA and rrnB), and they revealed closest similarity to Halobaculum gomorrense JCM 9908T, the single species with a validly published name of the genus Halobaculum , with similarity of 97.8 %. The rrnA and rrnB genes of both strains were 100 % similar. The rrnA genes were 97.6 % similar to the rrnB genes in both strains. DNA G+C contents of strains MGY-184T and MGY-205 were 67.0 and 67.4 mol%, respectively. Polar lipid analysis revealed that the two strains contained phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester derived from C20C20 archaeol. The DNA–DNA hybridization value between the two strains was 70 % and both strains showed low levels of DNA–DNA relatedness (48–50 %) with Halobaculum gomorrense JCM 9908T. Physiological and biochemical characteristics allowed differentiation of strains MGY-184T and MGY-205 from Halobaculum gomorrense JCM 9908T. Therefore, strains MGY-184T and MGY-205 represent a novel species of the genus Halobaculum , for which the name Halobaculum magnesiiphilum sp. nov. is proposed; the type strain is MGY-184T ( = JCM 17821T = KCTC 4100T).
A Gram-staining-negative, pleomorphic, aerobic, halophilic archaeon, designated strain 294-194-5T, was isolated in Japan from commercial solar salt imported from the Philippines. Colonies of strain 294-194-5T were translucent and red. Strain 294-194-5T was able to grow at 20–50 °C (optimum, 37–45 °C), with 14–30 % (w/v) NaCl (optimum, 18 %), and at pH 6.5–8.5 (optimum, pH 8.0). MgCl2 was not required for growth. Phylogenetic analysis based on 16S rRNA gene sequence similarities showed that strain 294-194-5T was most closely related to Natronoarchaeum mannanilyticum YSM-123T (96.8–97.1 % sequence similarities). The major polar lipids of the novel strain were the C20C20 and C20C25 derivatives of phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester and the same glycolipids (disulfated diglycosyl diether and one unidentified glycolipid) as detected in N. mannanilyticum YSM-123T. The DNA G+C content of strain 294-194-5T was 63.0 mol%. The DNA–DNA relatedness values between the novel strain and N. mannanilyticum YSM-123Twere 46.5 % and 48.5 % (reciprocal). Based on these data, strain 294-194-5T represents a novel species of the genus Natronoarchaeum , for which the name Natronoarchaeum philippinense sp. nov. is proposed. The type strain is 294-194-5T ( = JCM 16593T = CECT 7630T).
Three halophilic archaeal strains, MH1-34-1T, MH1-16-1 and MH1-224-5 were isolated from commercial salt samples produced from seawater in Indonesia, the Philippines and Japan, respectively. Cells of the three strains were pleomorphic and stained Gram-negative. Strain MH1-34-1T was orange–red pigmented, while MH1-16-1 and MH1-224-5 were pink-pigmented. Strain MH1-34-1T was able to grow at 12–30 % (w/v) NaCl (with optimum at 18 % NaCl, w/v) at pH 4.5–7.2 (optimum, pH 5.2–5.5) and at 15–45 °C (optimum, 42 °C). Strains MH1-16-1 and MH1-224-5 grew in slightly different ranges. These strains required at least 1 mM Mg2+ for growth. The 16S rRNA gene sequences of strains MH1-34-1T, MH1-16-1 and MH1-224-5 were almost identical (99.8–99.9 % similarities), and the closest relative was Halarchaeum acidiphilum MH-1-52-1T with 98.4 % similarities. The DNA G+C contents of MH1-34-1T, MH1-16-1 and MH1-224-5 were 59.3, 60.8 and 61.0 mol%, respectively. The level of DNA–DNA relatedness amongst the three strains was 90–91 %, while that between each of the three strains and Halarchaeum acidiphilum MH1-52-1T was 51–55 %. Based on the phenotypic, genotypic and phylogenetic analyses, it is proposed that the isolates should represent a novel species of the genus Halarchaeum , for which the name Halarchaeum salinum sp. nov. is proposed. The type strain is MH1-34-1T ( = JCM 16330T = CECT 7574T).