A New Methanogenic, Hydrogenotrophic Archaeon from Spitsbergen Permafrost

A new strain of methanogenic archaea, designated VT T , was isolated from a sample of Spitsbergen permafrost. The cells were nonmotile curved rods, 2.7–5.3 × 0.3 µm. The optimal conditions for growth were 20°C, pH 6.6, and NaCl concentrations 0.03–0.05 M. The H 2 /CO 2 gas mixture was the only substrate used. In the presence of H 2 /CO 2 , growth was stimulated by addition of yeast extract or rumen fluid. Phylogenetic analysis of the 16S rRNA gene sequences indicated that strain VT T belonged to the genus Methanobacterium and was most closely related to M. lacus 17A1 T (97.02% similarity). Comparison of the sequenced and assembled genome of strain VT T with the genomes of other members of this genus confirmed these results and revealed species-level differences. Our results indicate that this methanogenic isolate belongs to a new species of methanogenic archaea, for which the name Methanobacterium spitsbergense sp. nov. was proposed, with the type strain VT T (=VKM B-3566 T = JCM 39284 T ).