Candidatus Methanoperedens nitroreducens (M. nitroreducens)-like archaea, catalyzing anaerobic methane oxidation coupled with nitrate reduction, could play an important role in reducing methane emissions from paddy ecosystems. Currently, the spatial and temporal variations of the communities of M. nitroreducens-like archaea and the factors regulating their distribution in paddy soils are poorly known. Here, we examined the diversity, community composition and abundance of these anaerobic methanotrophs at four representative depths (0–10, 10–20, 20–30 and 30–40 cm) of paddy soils across four rice growth stages (tillering, jointing, flowering and milky stages). High-throughput sequencing of M. nitroreducens-like archaeal mcrA genes showed that their community structure varied among different depths. In contrast, the community structure of these archaea remained relatively stable across rice growth stages. Further, both soil depth and rice growth stage had a significant impact on the abundance of mcrA genes. The gene abundance varied from 7.6 × 10⁵ to 5.0 × 10⁶ copies g⁻¹ dry soil with higher values in 20–30 cm soils, and the abundance was found to be decreased from tillering to milky stages. The soil organic carbon content and ammonium content were the key factors affecting the community structure of these archaea. Our results indicated that both soil depth and crop growth stage greatly affected the abundance of M. nitroreducens-like archaea, while their community structure seemed to be more responsive to soil depth. Taken together, both space and time scales should be considered for better understanding the role of M. nitroreducens-like archaea reducing methane emissions from paddy ecosystems.

Candidatus Methanoperedens nitroreducens ( M. nitroreducens ) 样古菌，催化厌氧甲烷氧化和硝酸盐还原，可在减少稻田生态系统的甲烷排放方面发挥重要作用。目前，类硝基还原菌群落的时空变化及其在稻田土壤中分布的调控因素知之甚少。在这里，我们研究了水稻四个生长阶段（分蘖、拔节、拔节、拔节）四个代表性深度（0-10、10-20、20-30 和 30-40 厘米）稻田土壤中这些厌氧甲烷氧化菌的多样性、群落组成和丰度。开花和乳白色阶段）。M. nitroreducens样古菌mcr 的高通量测序A基因表明其群落结构在不同深度之间存在差异。相比之下，这些古细菌的群落结构在水稻生长阶段保持相对稳定。此外，土壤深度和水稻生长阶段对mcr A 基因的丰度有显着影响。基因丰度从7.6 × 10 ⁵到5.0 × 10 ⁶拷贝g ^-1干燥土壤不等，在20-30 cm 土壤中具有更高的值，并且发现丰度从分蘖期到乳熟期降低。土壤有机碳含量和铵态氮含量是影响这些古菌群落结构的关键因素。我们的结果表明，土壤深度和作物生长阶段都极大地影响了硝基还原菌的丰度类似古细菌，而它们的群落结构似乎对土壤深度更敏感。总之，应该考虑空间和时间尺度，以便更好地理解M. nitroreducens类古细菌在减少稻田生态系统甲烷排放方面的作用。