Active metabolic pathways of anaerobic methane oxidation in paddy soils

Anaerobic oxidation of methane (AOM) is a globally important CH4 sink. However, the AOM pathways in paddy soils, the largest agricultural source of methane emissions (31 Mio tons per year) are not yet well described. Here, a combination of 13C isotope tracer, phospholipid fatty acids (PLFA) analyses, and microbial community analysis was used to identify AOM pathways in fertilized (pig manure, biochar, NPK, and the control) paddy soils amended with alternative electron acceptors (AEAs) (NO3−, Fe3+, SO42−, humic acids, and the reference without AEAs addition). After 84 days of anaerobic incubation, the microbial co-occurrence network got tightened and became more complex relative to unincubated samples. Fertilization and AEAs addition led to a strong divergence of the microbial community structure as indicated by abundances of AOM-related microbiota and 13C incorporation into microbial PLFA, thus suggesting an environmental niche differentiation of AOM-involved microorganisms. Comparative analyses revealed a set of major and minor AOM pathways with synergistic relations to complementary anaerobic microbial groups. NO3−-driven AOM, performed by members of the candidate group ANME-2d, was the major AOM pathway. Minor AOM pathways involved NO2− reduction by NC10, reduction of humic acids and Fe3+ by Geobacter species, and SO42− reduction by sulfate-reducing bacteria linked with anaerobic methanotrophs. As identified by the network analysis, these active AOM pathways compensated a fraction of CH4 produced during ongoing methanogenesis. From a broader ecological perspective, nitrogen-driven AOM will become a more important methane sink in the future with the increases of nitrogen fertilization and deposition. © 2021 Elsevier Ltd

Fan L.1 , Schneider D.2 , Dippold M.A.3 , Poehlein A.2 , Wu W.3, 4 , Gui H.5 , Ge T.6 , Wu J.6 , Thiel V.7 , Kuzyakov Y. 1, 8, 9 , Dorodnikov M.1, 3
Elsevier Ltd
  • 1 Department of Soil Science of Temperate Ecosystems, University of Göttingen, Göttingen, 37077, Germany
  • 2 Institute for Microbiology and Genetics, University of Göttingen, Göttingen, 37077, Germany
  • 3 Department of Biogeochemistry of Agroecosystems, University of Göttingen, Göttingen, 37077, Germany
  • 4 Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm, 10691, Sweden
  • 5 Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
  • 6 Key Laboratory of Agro-ecological Processes in Subtropical Region & Changsha Research Station for Agricultural and Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of SciencesHunan 410125, China
  • 7 Geobiology, Geoscience Center, University of Göttingen, Göttingen, 37077, Germany
  • 8 Department of Agricultural Soil Science, University of Göttingen, Göttingen, 37077, Germany
  • 9 Agro-Technological Institute, RUDN University, Moscow, 117198, Russian Federation
Anaerobic oxidation of methane; CH4 turnover; Co-occurrence network; Greenhouse gas emission; Lipid biomarkers; Paddy soil
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