Methanolobus psychrotolerans sp. nov., a psychrotolerant methanoarchaeon isolated from a saline meromictic lake in Siberia.

A psychrotolerant, methylotrophic methanogen, strain YSF-03T , was isolated from the saline meromictic Lake Shira in Siberia. Cells of strain YSF-03T were non-motile, irregular cocci and 0.8-1.2 µm in diameter. The methanogenic substrates utilized by strain YSF-03T were methanol and trimethylamine. The temperature range of growth for strain YSF-03T was from 0 to 37 °C. The optimum growth conditions were 30-37 °C, pH 7.0-7.4 and 0.17 M NaCl. The G+C content of the genome of strain YSF-03T was 41.3 mol%. Phylogenetic analysis revealed that strain YSF-03T was most closely related to Methanolobus profundi MobMT (98.15 % similarity in 16S rRNA gene sequence). Genome relatedness between strain YSF-03T and MobMT was computed using the Genome-to-Genome Distance Calculator and average nucleotide identity, which gave values of 23.5 and 79.3 %, respectively. Based on the morphological, phenotypic, phylogenetic and genomic relatedness data presented here, it is evident that strain YSF-03T represents a novel species of the genus Methanolobus, for which the name Methanolobus psychrotolerans sp. nov. is proposed. The type strain is YSF-03T (=BCRC AR10049T =DSM 104044T =NBRC 112514T ).