title: Molecular diversity of methanotrophs in Transbaikal soda lake sediments and identification of potentially active populations by stable isotope probing.
abstract: Soda lakes are an environment with an unusually high pH and often high salinity. To identify the active methanotrophs in the Soda lake sediments, sediment slurries were incubated with a 10% (v/v) (13)CH(4) headspace and the (13)C-labelled DNA was subsequently extracted from these sediments following CsCl density gradient centrifugation. This DNA was then used as a template for PCR amplification of 16S rRNA genes and genes encoding PmoA and MmoX of methane monooxygenase, key enzymes in the methane oxidation pathway. Phylogenetic analysis of 16S rRNA genes, PmoA and MmoX identified that strains of Methylomicrobium, Methylobacter, Methylomonas and 'Methylothermus' had assimilated the (13)CH(4). Phylogenetic analysis of PmoA sequences amplified from DNA extracted from Soda lake sediments before Stable Isotope Probing (SIP) treatment showed that a much wider diversity of both type I and type II methanotroph sequences are present in this alkaline environment. The majority of methanotroph sequences detected in the (13)C-DNA studies were from type I methanotrophs, with 50% of 16S rRNA clones and 100% of pmoA clones from both Lake Suduntuiskii Torom and Lake Gorbunka suggesting that the type I methanotrophs are probably responsible for the majority of methane oxidation in this environment.
authors.affiliation: Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: Ju-Ling
authors.initials: JL
authors.lastname: Lin
authors.forename: Stefan
authors.initials: S
authors.lastname: Radajewski
authors.forename: Bulat T
authors.initials: BT
authors.lastname: Eshinimaev
authors.forename: Yuri A
authors.initials: YA
authors.lastname: Trotsenko
authors.forename: Ian R
authors.initials: IR
authors.lastname: McDonald
authors.forename: J Colin
authors.initials: JC
authors.lastname: Murrell
mesh_terms: D001483:Base Sequence; D002247:Carbon Isotopes; D002499:Centrifugation, Density Gradient; D002586:Cesium; D002712:Chlorides; D005618:Fresh Water; D014644:Genetic Variation; D019015:Geologic Sediments / Q000382:microbiology*; D007553:Isotope Labeling; D016013:Likelihood Functions; D008772:Methylococcaceae / Q000235:genetics*; D042083:Methylocystaceae / Q000235:genetics*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012426:Russia; D017422:Sequence Analysis, DNA
chemical_list: D002247:Carbon Isotopes; D002712:Chlorides; D012336:RNA, Ribosomal, 16S; D002586:Cesium; C028019:cesium chloride