Peatlands are important sources of CH4 emissions to the atmosphere and molecular surveys have identified a diverse, but mainly uncultured, euryarchaeal community in them. Characterization of a strain, E1-9cT, associated with uncultured group E1, from a minerotrophic fen is reported. Cells were regular cocci, usually found in pairs, that stained Gram-positive and were resistant to lysis by 0.1 % SDS. Multiple flagella were observed, but motility was not observed in wet mounts. Optimal growth was obtained at moderate temperatures (28–30 °C) and slightly acidic pH (5.5). Total Na+ and NaCl were only tolerated at concentrations less than 100 mM and 0.5 %, respectively, and Na2S concentrations above 0.1 mM were inhibitory. H2/CO2 and formate were the only methanogenic substrates used by E1-9cT; formate concentrations above 50 mM were inhibitory for growth. Vitamins, coenzyme M and acetate (4 mM) were required for growth and the doubling time was about 19 h. Phylogenetic analysis of the 16S rRNA gene and inferred McrA amino acid sequences showed that E1-9cT represented an independent lineage within the order Methanomicrobiales. Physiological and phylogenetic comparisons with different members of the order supported classification of E1-9cT in a new genus in the Methanomicrobiales. The name Methanosphaerula palustris gen. nov., sp. nov. is proposed; strain E1-9cT (=ATCC BAA-1565T =DSM 19958T) is the type strain of Methanosphaerula palustris.
A methanogenic organism from the domain Archaea (SD1T) was isolated from saline water released from a coal seam located 926 m below the surface via a methane-producing well near Monroe, Louisiana, USA. Growth and methanogenesis were supported with methanol, monomethylamine, dimethylamine or trimethylamine, but not with dimethylsulfide, formate, acetate or H2/CO2. Cells grew in high-salt minimal medium but growth was stimulated with yeast extract or tryptone. Cells were single, non-motile, irregular coccoids 0.5–1.0 μm in diameter and the cell wall contained protein. Conditions for the maximum rate of growth were 40–50 °C, 0.2–0.6 M NaCl, 100–≥200 mM MgCl2, and pH 7.0–8.0. The G+C content of the genomic DNA was 42±1mol %. A comparison of 16S rRNA gene sequences indicated that strain SD1T was most closely related to Methanolobus oregonensis DSM 5435T with 96 % gene sequence similarity. It is proposed that strain SD1T represents a novel species, Methanolobus zinderi sp. nov. The type strain is SD1T (=ATCC BAA-1601T=DSM 21339T).