Three thermo-tolerant halophilic archaeal strains, SR-441T, SR-412 and SR-188, were isolated from commercial salt samples. Cells were non-motile pleomorphic rod-shaped, and stained Gram-negative. Colonies were pink-pigmented. The three strains were able to grow with 1.7–4.6 M NaCl (optimum, 2.5 M), at pH 6.5–9.0 (optimum, pH 8.0) and at 35–60 °C (optimum, 45 °C). The orthologous 16S rRNA gene sequence similarities amongst the three strains were 98.8–99.3 %, and the level of DNA–DNA relatedness was 71–74 and 72–75 % (reciprocally). The closest relative was Halopiger aswanensis JCM 11628T with 98.6 %–99.1 % similarity in the orthologous 16S rRNA gene sequences, followed by two more Halopiger species, Halopiger xanaduensis JCM 14033T (98.5 %–99.1 %) and Halopiger salifodinae JCM 9578T (95.5 %–95.6 %). DNA–DNA relatednesses between the three strains and H. aswanensis JCM 11628T and H. xanaduensis JCM 14033T were 61 and 54 %, respectively. The polar lipids of the three novel strains were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, and bis-sulfated diglycosyl archaeol-1. The most distinctive feature of the three strains was the ability to grow at 60 °C, while the maximum growth temperature of H. aswanensis is 55 °C. Based on phenotypic and phylogenetic analyses, the isolates are considered to represent a novel species of the genus Halopiger , for which the name Halopiger thermotolerans sp. nov. is proposed. The type strain is SR-441T (=JCM 19583T=KCTC 4248T) isolated from solar salt produced in Australia. SR-412 (=JCM 19582) and SR-188 (=JCM 19581) isolated from commercial salt samples are additional strains of the species.
A Gram-stain-negative, rod-pleomorphic, aerobic, halophilic archaeon, strain MK62-1T, was isolated from commercial salt made from seawater in the Philippines. Strain MK62-1T was able to grow at 2.1–4.7 M NaCl (with optimum at 2.1–2.6 M NaCl), pH 6.5–9.5 (optimum, pH 7.0–7.5) and 20–55 °C (optimum, 45–50 °C). Based on the orthologous 16S rRNA gene sequence, the closest relative was Haloparvum sedimenti JCM 30891T with 99.2 % similarity. The RNA polymerase subunit B′ gene sequence also showed the highest similarity (97.4 %) to that of Haloparvum sedimenti DYS4T. The DNA G+C content of MK62-1T was 70.1 mol%, while that of Haloparvum sedimenti JCM 30891T was 69.5 mol% by the HPLC method. The levels of DNA–DNA relatedness between MK62-1T and Haloparvum sedimenti JCM 30891T were 60.6 and 60.8 % (reciprocally). The major polar lipids of the isolate were C20C20 archaeol derivatives of phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and phosphatidylglycerol sulfate. Based on the phenotypic and phylogenetic analyses, it is proposed that the isolate represents species within the genus Haloparvum , for which the name Haloparvum alkalitolerans sp. nov. is proposed. The type strain is MK62-1T (=JCM 30442T =KCTC 4214T).