Active metabolic pathways of anaerobic methane oxidation in paddy soils
Active metabolic pathways of anaerobic methane oxidation in paddy soils
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DOI：
10.1016/j.soilbio.2021.108215
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发表时间：
2021-03-24
影响因子：
9.7
通讯作者：
Dorodnikov, Maxim
中科院分区：
文献类型：
--
作者：
Fan, Lichao;Schneider, Dominik;Dorodnikov, Maxim
甲烷厌氧氧化(AOM)是全球重要的甲烷汇。然而，稻田土壤中的AOM途径还没有得到很好的描述，稻田土壤是甲烷排放的最大农业来源(每年3100万吨)。在这里，结合C-13同位素示踪剂、磷脂脂肪酸(PLFA)分析和微生物群落分析，确定了经过替代电子受体(AEAs)(NO3-、Fe3+、SO42-、腐殖酸和未添加AEAs的参照物)改良的水稻土(猪粪、生物炭、NPK和对照)中的AOM途径。厌氧培养84天后，微生物共生网络变得更加紧密，与未培养的样品相比变得更加复杂。施肥和AEAs的添加导致了微生物群落结构的强烈分化，与AOM相关的微生物区系和C-13掺入微生物PLFA的丰富性表明，AOM相关微生物的环境生态位分化。比较分析揭示了一系列主要和次要的AOM途径，它们与互补的厌氧微生物群具有协同关系。由候选基因ANME-2d的成员执行的NO3驱动的AOM是主要的AOM途径。次要的AOM途径包括NC10还原NO2-，地杆菌还原腐殖酸和Fe3+，硫酸盐还原细菌结合厌氧甲烷氧化菌还原SO42-。正如网络分析所确定的那样，这些活跃的AOM途径补偿了正在进行的甲烷生成过程中产生的一小部分CH4。从更广阔的生态学角度来看，随着氮肥施用量和沉降量的增加，氮素固定的AOM将成为未来更重要的甲烷汇。
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 C-13 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 C-13 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, nitrogendriven AOM will become a more important methane sink in the future with the increases of nitrogen fertilization and deposition.