A novel, strictly anaerobic, methylotrophic marine methanogen, strain SLH33T, was isolated from deep sediment samples covered by an orange microbial mat collected from the Napoli Mud Volcano. Cells of strain SLH33T were Gram-stain-negative, motile, irregular cocci that occurred singly. Cells utilized trimethylamine, dimethylamine, monomethylamine, methanol, betaine, N,N-dimethylethanolamine and choline (N,N,N-trimethylethanolamine) as substrates for growth and methanogenesis. The optimal growth temperature was 30 °C; maximum growth rate was obtained at pH 7.0 in the presence of 0.5 M Na+. The DNA G+C content of strain SLH33T was 43.4 mol%. Phylogenetic analyses based on 16S rRNA gene sequences placed strain SLH33T within the genus Methanococcoides . The novel isolate was related most closely to Methanococcoides methylutens TMA-10T (98.8 % 16S rRNA gene sequence similarity) but distantly related to Methanococcoides burtonii DSM 6242T (97.6 %) and Methanococcoides alaskense AK-5T (97.6 %). DNA–DNA hybridization studies indicated that strain SLH33T represents a novel species, given that it shared less than 16 % DNA–DNA relatedness with Methanococcoides methylutens TMA-10T. The name Methanococcoides vulcani sp. nov. is proposed for this novel species, with strain SLH33T ( = DSM 26966T = JCM 19278T) as the type strain. An emended description of the genus Methanococcoides is also proposed.
Halophilic archaeal strain GX10T was isolated from the Gangxi marine solar saltern in China. Strain GX10T was observed to have pleomorphic cells that lysed in distilled water, stained Gram-negative and produced red-pigmented colonies. Strain GX10T was able to grow at 20–50 °C (optimum 37 °C), with 1.4–4.8 M NaCl (optimum 3.1 M NaCl), with 0–0.7 M MgCl2 (optimum 0.05 M MgCl2) and at pH 5.0–9.0 (optimum pH 7.0). The major polar lipids of strain GX10T were identified as phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, two major glycolipids chromatographically identical to sulfated mannosyl glucosyl diether and mannosyl glucosyl diether, and five unidentified glycolipids. Phylogenetic tree reconstructions based on 16S rRNA gene and rpoB′ sequences revealed that strain GX10T was distinct from the related genera, Halogranum , Haloferax , Halopelagius , Halogeometricum , Halobellus , Haloplanus and Halorubrum . The DNA G+C content of strain GX10T was 62.9 mol%. The phenotypic, chemotaxonomic and phylogenetic properties suggested that strain GX10T represents a novel species of a new genus within the family Halobacteriaceae , for which the name Salinigranum rubrum gen. nov., sp. nov. is proposed. The type strain of the type species is GX10T ( = CGMCC 1.10385T = JCM 17116T).
A mesophilic, slightly halophilic, obligately methylotrophic, methanogenic archaeon, designated strain GTA13T, was isolated from natural gas-bearing confined aquifers in the Minami-Kanto gas field, Japan. The cells were non-motile, slightly irregular cocci, 0.7–1.0 µm in diameter and occurred singly, in pairs or as small aggregates. The cells grew with tri- or dimethylamine but not with H2/CO2, formate, acetate, methanol or dimethyl sulphide. Vitamins, sodium and magnesium were required for growth. Optimal growth occurred at pH 7.0–7.5, 35 °C, 0.35–0.40 M NaCl and 15–50 mM MgCl2. The NaCl range for growth was 0.2–1.3 M. The DNA G+C content was 43.7 mol%. Strain GTA13T showed highest levels of 16S rRNA gene sequence similarity with Methanohalophilus portucalensis FDF-1T (96.4 % sequence similarity) and Methanohalophilus halophilus DSM 3094T (96.0 %). On the basis of physiological and phylogenetic features, strain GTA13T is considered to represent a novel species of the genus Methanohalophilus , for which the name Methanohalophilus levihalophilus sp. nov. is proposed. The type strain is GTA13T ( = NBRC 110099T = DSM 28452T). An emended description of the genus Methanohalophilus is also proposed.