title: Gammaproteobacterial methanotrophs dominate cold methane seeps in floodplains of West Siberian rivers.
abstract: A complex system of muddy fluid-discharging and methane (CH4)-releasing seeps was discovered in a valley of the river Mukhrinskaya, one of the small rivers of the Irtysh Basin, West Siberia. CH4 flux from most (90%) of these gas ebullition sites did not exceed 1.45 g CH4 h(-1), while some seeps emitted up to 5.54 g CH4 h(-1). The δ(13)C value of methane released from these seeps varied between -71.1 and -71.3‰, suggesting its biogenic origin. Although the seeps were characterized by low in situ temperatures (3.5 to 5°C), relatively high rates of methane oxidation (15.5 to 15.9 nmol CH4 ml(-1) day(-1)) were measured in mud samples. Fluorescence in situ hybridization detected 10(7) methanotrophic bacteria (MB) per g of mud (dry weight), which accounted for up to 20.5% of total bacterial cell counts. Most (95.8 to 99.3%) methanotroph cells were type I (gammaproteobacterial) MB. The diversity of methanotrophs in this habitat was further assessed by pyrosequencing of pmoA genes, encoding particulate methane monooxygenase. A total of 53,828 pmoA gene sequences of seep-inhabiting methanotrophs were retrieved and analyzed. Nearly all of these sequences affiliated with type I MB, including the Methylobacter-Methylovulum-Methylosoma group, lake cluster 2, and several as-yet-uncharacterized methanotroph clades. Apparently, microbial communities attenuating methane fluxes from these local but strong CH4 sources in floodplains of high-latitude rivers have a large proportion of potentially novel, psychrotolerant methanotrophs, thereby providing a challenge for future isolation studies.
authors: S. N. Winogradsky Institute of Microbiology, Russian Academy of Sciences, Moscow, Russia.
authors: Igor Y
authors: IY
authors: Oshkin
authors: Max-Planck-Institut für terrestrische Mikrobiologie, Marburg, Germany.
authors: Carl-Eric
authors: CE
authors: Wegner
authors: Radboud University Nijmegen, Nijmegen, The Netherlands.
authors: Claudia
authors: C
authors: Lüke
authors: Moscow State University, Moscow, Russia Laboratory of Computational Geophysics, Tomsk State University, Tomsk, Russia Yugra State University, Khanty-Mansiysk, Russia Institute of Forest Science, Russian Academy of Sciences, Uspenskoe, Russia.
authors: Mikhail V
authors: MV
authors: Glagolev
authors: Yugra State University, Khanty-Mansiysk, Russia.
authors: Illiya V
authors: IV
authors: Filippov
authors: S. N. Winogradsky Institute of Microbiology, Russian Academy of Sciences, Moscow, Russia.
authors: Nikolay V
authors: NV
authors: Pimenov
authors: Max-Planck-Institut für terrestrische Mikrobiologie, Marburg, Germany Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, Marburg, Germany.
authors: Werner
authors: W
authors: Liesack
authors: S. N. Winogradsky Institute of Microbiology, Russian Academy of Sciences, Moscow, Russia dedysh@mail.ru.
authors: Svetlana N
authors: SN
authors: Dedysh
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D003080:Cold Temperature; D017753:Ecosystem; D020563:Gammaproteobacteria / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D059014:High-Throughput Nucleotide Sequencing; D017404:In Situ Hybridization, Fluorescence; D008697:Methane / Q000737:chemistry / Q000378:metabolism*; D008772:Methylococcaceae / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010105:Oxygenases / Q000235:genetics*; D010802:Phylogeny; D045483:Rivers; D017422:Sequence Analysis, DNA; D012800:Siberia
chemical_list: D001426:Bacterial Proteins; D010105:Oxygenases; C021555:methane monooxygenase; D008697:Methane