Two novel thermophilic and slightly acidophilic strains, Kam940T and Kam1507b, which shared 99 % 16S rRNA gene sequence identity, were isolated from terrestrial hot springs of the Uzon caldera on the Kamchatka peninsula. Cells of both strains were non-motile, regular cocci. Growth was observed between 55 and 85 °C, with an optimum at 65–70 °C (doubling time, 6.1 h), and at pH 4.5–7.5, with optimum growth at pH 5.5–6.0. The isolates were strictly anaerobic organotrophs and grew on a narrow spectrum of energy-rich substrates, such as beef extract, gelatin, peptone, pyruvate, sucrose and yeast extract, with yields above 107 cells ml−1. Sulfate, sulfite, thiosulfate and nitrate added as potential electron acceptors did not stimulate growth when tested with peptone. H2 at 100 % in the gas phase inhibited growth on peptone. Glycerol dibiphytanyl glycerol tetraethers (GDGTs) with zero to four cyclopentyl rings were present in the lipid fraction of isolate Kam940T. The G+C content of the genomic DNA of strain Kam940T was 37 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolates were archaea of the phylum Crenarchaeota, only distantly related to the cultured members of the class Thermoprotei (no more than 89 % identity), and formed an independent lineage adjacent to the orders Desulfurococcales and Acidilobales and clustering only with uncultured clones from hot springs of Yellowstone National Park and Iceland as the closest relatives. On the basis of their phylogenetic position and novel phenotypic features, isolates Kam940T and Kam1507b are proposed to be assigned to a new genus and species, Fervidicoccus fontis gen. nov., sp. nov. The type strain of Fervidicoccus fontis is strain Kam940T (=DSM 19380T =VKM B-2539T). The phylogenetic data as well as phenotypic properties suggest that the novel crenarchaeotes form the basis of a new family, Fervidicoccaceae fam. nov., and order, Fervidicoccales ord. nov., within the class Thermoprotei.
Two extremely halophilic archaea, strains RO5-2T and RO5-14, were isolated from Rudong marine solar saltern in Jiangsu, China. Cells of the two strains were pleomorphic, motile and stained Gram-negative. Colonies were red-pigmented. Strains RO5-2T and RO5-14 were able to grow at 20–50 °C (optimum 37 °C), at 2.6–4.8 M NaCl (optimum 3.4–3.9 M NaCl), at 0.03–0.7 M MgCl2 (optimum 0.5 M MgCl2) and at pH 5.5–8.0 (optimum pH 6.5–7.0). Cells lyse in distilled water and the minimal NaCl concentration to prevent cell lysis was 12 % (w/v). The major polar lipids of the two strains were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and two major glycolipids chromatographically identical to sulfated mannosyl glucosyl diether (S-DGD-1) and mannosyl glucosyl diether (DGD-1). The 16S rRNA gene sequences of strains RO5-2T and RO5-14 showed 93.4–93.8 % similarity to the closest cultivated relative, Halosarcina pallida. The DNA G+C content of strains RO5-2T and RO5-14 was 61.0 mol% and 59.9 mol%, respectively. The DNA–DNA relatedness between strains RO5-2T and RO5-14 was 86.0 %. The phenotypic, chemotaxonomic and phylogenetic properties suggest that strains RO5-2T and RO5-14 represent a novel species in a new genus within the family Halobacteriaceae, for which the name Halopelagius inordinatus gen. nov., sp. nov. is proposed. The type strain is RO5-2T (=CGMCC 1.7739T =JCM 15773T).
An obligately anaerobic, methanogenic archaeon, strain HCT, was isolated from soil of the Zoige wetland on the Tibetan plateau, China. The strain was isolated through construction of an artificial butyrate-degrading consortium in co-culture with a syntrophic bacterium, ‘Syntrophomonas erecta subsp. sporosyntropha’ JCM 13344. Cells of strain HCT were irregular coccoids, 0.8–2 μm in diameter, that occurred singly and utilized only H2/CO2 for growth and methane production. Growth occurred at 18–45 °C (optimum around 37 °C). The pH for growth was 5.0–8.5 (optimal growth around pH 6.6). The G+C content of the genomic DNA was 60.2 mol%. 16S rRNA gene sequence analysis indicated that strain HCT was affiliated to the genus Methanoculleus, with sequence similarities of 94.8–97.2 % to existing members. However, strain HCT was distinguished from described Methanoculleus species by not using formate for growth or methane formation and not requiring acetate as a growth factor. On the basis of phylogenetic analysis and phenotypic characteristics, the novel species Methanoculleus hydrogenitrophicus sp. nov. is proposed, with strain HCT (=CGMCC 1.5146T =JCM 16311T) as the type strain.