Methylorosula polaris gen. nov., sp. nov., an aerobic, facultatively methylotrophic psychrotolerant bacterium from tundra wetland soil

Abstract

Three strains of Gram-negative, aerobic, motile bacteria with bipolar flagella were isolated from acidic tundra wetland soils near the city of Vorkuta and from the Chukotka and Yugorsky Peninsulas and designated strains V-022T, Ch-022 and Ju-022. The cells were rod-shaped, 0.5–0.6 µm in width and 1.3–4.5 µm in length and reproduced by irregular fission. These bacteria were facultative methylotrophs that used methanol, methylamines and a wide range of other sources of carbon and energy such as sugars and polysaccharides, ethanol and amino acids. The isolates used the Calvin–Benson pathway for the assimilation of one-carbon compounds and were unable to fix nitrogen. The new strains were moderately acidophilic and psychrotolerant, capable of growth over a pH range of 4.0 to 7.8, with optimum growth at pH 5.5–6.0. Growth occurred between 4 and 30 °C (optimum 20–25 °C). The principal phospholipid fatty acid was C18 : 1ω7c. The DNA G+C content of strain V-022Twas 65.2 mol%. Analysis of the 16S rRNA gene sequences revealed that all three isolates V-022T, Ch-022 and Yu-022 exhibited almost identical 16S rRNA gene sequences (99.9 % gene sequence similarity) and formed a new lineage within the classAlphaproteobacteria. The nameMethylorosula polarisis suggested to accommodate this new genus and novel species with strain V-022T( = DSM 22001T = VKM V-2485T) as the type strain of the type species.