title: A temperate river estuary is a sink for methanotrophs adapted to extremes of pH, temperature and salinity.
abstract: River Tyne (UK) estuarine sediments harbour a genetically and functionally diverse community of methane-oxidizing bacteria (methanotrophs), the composition and activity of which were directly influenced by imposed environmental conditions (pH, salinity, temperature) that extended far beyond those found in situ. In aerobic sediment slurries methane oxidation rates were monitored together with the diversity of a functional gene marker for methanotrophs (pmoA). Under near in situ conditions (4-30°C, pH 6-8, 1-15 g l(-1) NaCl), communities were enriched by sequences affiliated with Methylobacter and Methylomonas spp. and specifically a Methylobacter psychrophilus-related species at 4-21°C. More extreme conditions, namely high temperatures ≥ 40°C, high ≥ 9 and low ≤ 5 pH, and high salinities ≥ 35 g l(-1) selected for putative thermophiles (Methylocaldum), acidophiles (Methylosoma) and haloalkaliphiles (Methylomicrobium). The presence of these extreme methanotrophs (unlikely to be part of the active community in situ) indicates passive dispersal from surrounding environments into the estuary.
authors.affiliation: School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
authors.forename: Angela
authors.initials: A
authors.lastname: Sherry
authors.affiliation: School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
authors.forename: Kate A
authors.initials: KA
authors.lastname: Osborne
authors.affiliation: School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
authors.forename: Frances R
authors.initials: FR
authors.lastname: Sidgwick
authors.affiliation: School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
authors.forename: Neil D
authors.initials: ND
authors.lastname: Gray
authors.affiliation: School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
authors.forename: Helen M
authors.initials: HM
authors.lastname: Talbot
mesh_terms: D000332:Aerobiosis; D058448:Biota / Q000187:drug effects* / Q000528:radiation effects*; D063366:Estuaries; D005618:Fresh Water / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000378:metabolism*; D008772:Methylococcaceae / Q000145:classification* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D054712:Salinity; D012965:Sodium Chloride / Q000378:metabolism; D013696:Temperature; D006113:United Kingdom
chemical_list: D012965:Sodium Chloride; D008697:Methane