title: Anaerobic oxidation of methane associated with sulfate reduction in a natural freshwater gas source.
abstract: The occurrence of anaerobic oxidation of methane (AOM) and trace methane oxidation (TMO) was investigated in a freshwater natural gas source. Sediment samples were taken and analyzed for potential electron acceptors coupled to AOM. Long-term incubations with (13)C-labeled CH4 ((13)CH4) and different electron acceptors showed that both AOM and TMO occurred. In most conditions, (13)C-labeled CO2 ((13)CO2) simultaneously increased with methane formation, which is typical for TMO. In the presence of nitrate, neither methane formation nor methane oxidation occurred. Net AOM was measured only with sulfate as electron acceptor. Here, sulfide production occurred simultaneously with (13)CO2 production and no methanogenesis occurred, excluding TMO as a possible source for (13)CO2 production from (13)CH4. Archaeal 16S rRNA gene analysis showed the highest presence of ANME-2a/b (ANaerobic MEthane oxidizing archaea) and AAA (AOM Associated Archaea) sequences in the incubations with methane and sulfate as compared with only methane addition. Higher abundance of ANME-2a/b in incubations with methane and sulfate as compared with only sulfate addition was shown by qPCR analysis. Bacterial 16S rRNA gene analysis showed the presence of sulfate-reducing bacteria belonging to SEEP-SRB1. This is the first report that explicitly shows that AOM is associated with sulfate reduction in an enrichment culture of ANME-2a/b and AAA methanotrophs and SEEP-SRB1 sulfate reducers from a low-saline environment.
authors.affiliation: Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands.
authors.forename: Peer Ha
authors.initials: PH
authors.lastname: Timmers
authors.affiliation: Sub-department of Environmental Technology, Wageningen University, Wageningen, The Netherlands.
authors.forename: Diego A
authors.initials: DA
authors.lastname: Suarez-Zuluaga
authors.affiliation: Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands.
authors.forename: Minke
authors.initials: M
authors.lastname: van Rossem
authors.affiliation: Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands.
authors.forename: Martijn
authors.initials: M
authors.lastname: Diender
authors.affiliation: Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands.|Centre of Biological Engineering, University of Minho, Campus de Gualtar, Braga, Portugal.
authors.forename: Alfons Jm
authors.initials: AJ
authors.lastname: Stams
authors.affiliation: Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands.|Wetsus, European Centre of Excellence for Sustainable Water Technology, Leeuwarden, the Netherlands.
authors.forename: Caroline M
authors.identifier: 0000-0002-3391-7742
authors.initials: CM
authors.lastname: Plugge
mesh_terms: D000693:Anaerobiosis; D001105:Archaea / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002247:Carbon Isotopes / Q000032:analysis; D005618:Fresh Water / Q000737:chemistry / Q000382:microbiology; D019015:Geologic Sediments / Q000737:chemistry / Q000382:microbiology; D008697:Methane / Q000378:metabolism*; D059206:Natural Gas; D009566:Nitrates / Q000378:metabolism; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013431:Sulfates / Q000378:metabolism*; D013440:Sulfides / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D059206:Natural Gas; D009566:Nitrates; D012336:RNA, Ribosomal, 16S; D013431:Sulfates; D013440:Sulfides; D008697:Methane