Methylocella tundrae sp. nov., a novel methanotrophic bacterium from acidic tundra peatlands

1 Institute of Microbiology, Russian Academy of Sciences, Moscow 117312, Russia 2 Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow Region 142292, Russia 3 Max-Planck-Institut für terrestrische Mikrobiologie, D-35043 Marburg, Germany Correspondence Svetlana N. Dedysh s.dedysh{at}mtu-net.ru A novel species, Methylocella tundrae , is proposed for three methanotrophic strains (T4 T , TCh1 and TY1) isolated from acidic Sphagnum tundra peatlands. These strains are aerobic, Gram-negative, non-motile, dinitrogen-fixing rods that possess a soluble methane monooxygenase and utilize the serine pathway for carbon assimilation. Strains T4 T , TCh1 and TY1 are moderately acidophilic organisms capable of growth between pH 4·2 and 7·5 (optimum 5·5–6·0) and between 5 and 30 °C (optimum 15 °C). The major phospholipid fatty acid is 18 : 1 7 c . The DNA G+C content of strain T4 T is 63·3 mol%. The three strains possess almost identical 16S rRNA gene sequences and are most closely related to two previously identified species of Methylocella , Methylocella palustris (97 % similarity) and Methylocella silvestris (97·5 % similarity). DNA–DNA hybridization values of strain T4 T with Methylocella palustris K T and Methylocella silvestris BL2 T were respectively 27 and 36 %. Thus, the tundra strains represent a novel species, for which the name Methylocella tundrae sp. nov. is proposed. Strain T4 T (=DSM 15673 T =NCIMB 13949 T ) is the type strain. Abbreviations: ICM, intracytoplasmic membrane; PLFA, phospholipid fatty acid; sMMO, soluble methane monooxygenase Published online ahead of print on 25 July 2003 as DOI 10.1099/ijs.0.02805-0. The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene sequence and partial sequences of the mmoX and mxaF genes of Methylocella tundrae strain T4 T are respectively AJ555244 , AJ555245 and AJ555246 .