title: Field-scale labelling and activity quantification of methane-oxidizing bacteria in a landfill-cover soil.
abstract: Aerobic methane-oxidizing bacteria (MOB) play an important role in soils, mitigating emissions of the greenhouse gas methane (CH(4)) to the atmosphere. Here, we combined stable isotope probing on MOB-specific phospholipid fatty acids (PLFA-SIP) with field-based gas push-pull tests (GPPTs). This novel approach (SIP-GPPT) was tested in a landfill-cover soil at four locations with different MOB activity. Potential oxidation rates derived from regular- and SIP-GPPTs agreed well and ranged from 0.2 to 52.8 mmol CH(4) (L soil air)(-1) day(-1). PLFA profiles of soil extracts mainly contained C(14) to C(18) fatty acids (FAs), with a dominance of C(16) FAs. Uptake of (13) C into MOB biomass during SIP-GPPTs was clearly indicated by increased δ(13)C values (up to c. 1500‰) of MOB-characteristic FAs. In addition, (13)C incorporation increased with CH(4) oxidation rates. In general, FAs C(14:0) , C(16:1ω8), C(16:1ω7) and C(16:1ω6) (type I MOB) showed highest (13)C incorporation, while substantial (13)C incorporation into FAs C(18:1ω8) and C(18:1ω7) (type II MOB) was only observed at high-activity locations. Our findings demonstrate the applicability of the SIP-GPPT approach for in situ quantification of potential CH(4) oxidation rates and simultaneous labelling of active MOB, suggesting a dominance of type I MOB over type II MOB in the CH(4)-oxidizing community in this landfill-cover soil.
authors.affiliation: Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Zurich, Switzerland.
authors.forename: Ruth
authors.initials: R
authors.lastname: Henneberger
authors.forename: Eleonora
authors.initials: E
authors.lastname: Chiri
authors.forename: Jan
authors.initials: J
authors.lastname: Blees
authors.forename: Helge
authors.initials: H
authors.lastname: Niemann
authors.forename: Moritz F
authors.initials: MF
authors.lastname: Lehmann
authors.forename: Martin H
authors.initials: MH
authors.lastname: Schroth
mesh_terms: D002247:Carbon Isotopes; D005227:Fatty Acids / Q000032:analysis / Q000378:metabolism; D005740:Gases / Q000378:metabolism; D008697:Methane / Q000378:metabolism; D008772:Methylococcaceae / Q000378:metabolism*; D010084:Oxidation-Reduction; D010743:Phospholipids / Q000737:chemistry; D012037:Refuse Disposal; D012988:Soil Microbiology
chemical_list: D002247:Carbon Isotopes; D005227:Fatty Acids; D005740:Gases; D010743:Phospholipids; D008697:Methane