Two halophilic archaeal strains, R2T and R27T, were isolated from the brown alga Laminaria produced at Dalian, Liaoning Province, China. Both had pleomorphic cells that lysed in distilled water, stained Gram-negative and formed red-pigmented colonies. They grew optimally at 42 °C, pH 7.0 and in the presence of 3.1–3.4 M NaCl and 0.03–0.5 M Mg2+. The major polar lipids of the two strains were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me) and four major glycolipids chromatographically identical to those of Halosimplex carlsbadense JCM 11222T. 16S rRNA gene analysis revealed that each strain had two dissimilar 16S rRNA genes and both strains were phylogenetically related to Halosimplex carlsbadense JCM 11222T (92.7–98.8 % similarities). The rpoB′ gene similarities between strains R2T and R27T and between these strains and Halosimplex carlsbadense JCM 11222T were 95.7 %, 96.1 % and 95.8 %, respectively. The DNA G+C contents of strains R2T and R27T were 62.5 mol% and 64.0 mol%, respectively. The DNA–DNA hybridization values between strains R2T and R27T and between the two strains and Halosimplex carlsbadense JCM 11222T were 43 %, 52 % and 47 %, respectively. It was concluded that strain R2T ( = CGMCC 1.10586T = JCM 17263T) and strain R27T ( = CGMCC 1.10591T = JCM 17268T) represent two novel species of the genus Halosimplex , for which the names Halosimplex pelagicum sp. nov. and Halosimplex rubrum sp. nov. are proposed. An emended description of the genus Halosimplex is also presented.
A psychrotolerant hydrogenotrophic methanogen, strain Pt1, was isolated from a syntrophic propionate-oxidizing methanogenic consortium obtained from granulated biomass of a two-stage low-temperature (3–8 °C) anaerobic expanded granular sludge bed (EGSB) bioreactor, fed with a mixture of volatile fatty acids (VFAs) (acetate, propionate and butyrate). The strain was strictly anaerobic, and cells were curved rods, 0.4–0.5×7.5–25 µm, that sometimes formed wavy filaments from 25 to several hundred micrometres in length. Cells stained Gram-negative and were non-sporulating. They were gently motile by means of tufted flagella. The strain grew at 5–37 °C (optimum at 20–30 °C), at pH 6.0–10 (optimum 7.0–7.5) and with 0–0.3 M NaCl (optimum 0 M NaCl). Growth and methane production was found with H2/CO2 and very weak growth with formate. Acetate and yeast extract stimulated growth, but were not essential. The G+C content of the DNA of strain Pt1 was 40 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain Pt1 was a member of the genus Methanospirillum and showed 97.5 % sequence similarity to Methanospirillum hungatei JF1T and 94 % sequence similarity to Methanospirillum lacunae Ki8-1T. DNA–DNA hybridization of strain Pt1 with Methanospirillum hungatei JF1T revealed 39 % relatedness. On the basis of its phenotypic characteristics and phylogenetic position, strain Pt1 is a representative of a novel species of the genus Methanospirillum , for which the name Methanospirillum stamsii sp. nov. is proposed. The type strain is Pt1T ( = DSM 26304T = VKM B-2808T).