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

A psychrotolerant, methylotrophic methanogen, strain YSF-03(T), was isolated from the saline meromictic Lake Shira in Siberia. Cells of strain YSF-03(T) were non-motile, irregular cocci and 0.8-1.2 mu m in diameter. The methanogenic substrates utilized by strain YSF-03(T) were methanol and trimethylamine. The temperature range of growth for strain YSF-03(T) was from 0 to 37 degrees C. The optimum growth conditions were 30-37 degrees C, pH 7.0-7.4 and 0.17M NaCl. The G+C content of the genome of strain YSF-03(T) was 41.3 mol%. Phylogenetic analysis revealed that strain YSF-03(T) was most closely related to Methanolobus profundi MobM(T) (98.15% similarity in 16S rRNA gene sequence). Genome relatedness between strain YSF-03(T) and MobM(T) 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-03(T) represents a novel species of the genus Methanolobus, for which the name Methanolobus psychrotolerans sp. nov. is proposed. The type strain is YSF-03(T) (= BCRC AR10049(T) = DSM 104044(T) = NBRC 112514(T)).