College of Chemistry and Materials Engineering, Quzhou University, Quzhou 324000, China.
Jiangsu Key Laboratory of Agricultural Meteorology, School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China.
Sci Total Environ. 2022 Dec 10;851(Pt 2):158288. doi: 10.1016/j.scitotenv.2022.158288. Epub 2022 Aug 27.
Rivers are an important site for methane emissions and reactive nitrogen removal. The process of nitrite-dependent anaerobic methane oxidation (n-damo) links the global carbon cycle and the nitrogen cycle, but its role in methane mitigation and nitrogen removal in rivers is poorly known. In the present study, we investigated the activity, abundance, and community composition of n-damo bacteria in sediment of the upper, middle, and lower reaches of Wuxijiang River (Zhejiang Province, China). The CH stable isotope experiments showed that the methane oxidation activity of n-damo was 0.11-1.88 nmol CO g (dry sediment) d, and the activity measured from the middle reaches was significantly higher than that from the remaining regions. It was estimated that 3.27 g CH m year and 8.72 g N m year could be consumed via n-damo. Quantitative PCR confirmed the presence of n-damo bacteria, and their 16S rRNA gene abundance varied between 5.45 × 10 and 5.86 × 10 copies g dry sediment. Similarly, the abundance of n-damo bacteria was significantly higher in the middle reaches. High-throughput sequencing showed a high n-damo bacterial diversity, with totally 152 operational taxonomic units being detected at 97 % sequence similarity cut-off. In addition, the n-damo bacterial community composition also varied spatially. The inorganic nitrogen (NH, NO, NO) level was found to be the key environmental factor controlling the n-damo activity and bacterial community composition. Overall, our results showed the spatial variations and environmental regulation of the activity and community structure of n-damo bacteria in river sediment, which expanded our understanding of the quantitative importance of n-damo in both methane oxidation and reactive nitrogen removal in riverine systems.
河流是甲烷排放和反应性氮去除的重要场所。亚硝酸盐依赖型厌氧甲烷氧化（n-damo）过程将全球碳循环和氮循环联系起来，但它在河流中甲烷减排和氮去除中的作用知之甚少。本研究调查了中国浙江省乌溪江上游、中游和下游沉积物中 n-damo 细菌的活性、丰度和群落组成。CH 稳定同位素实验表明，n-damo 的甲烷氧化活性为 0.11-1.88 nmol CO g（干沉积物）d，中游的活性明显高于其余地区。据估计，n-damo 可消耗 3.27 g CH m year 和 8.72 g N m year。定量 PCR 证实了 n-damo 细菌的存在，其 16S rRNA 基因丰度在 5.45×10 和 5.86×10 拷贝 g 干沉积物之间变化。同样，中游的 n-damo 细菌丰度也显著更高。高通量测序显示 n-damo 细菌具有很高的多样性，在 97%序列相似性截断处共检测到 152 个操作分类单元。此外，n-damo 细菌群落组成也存在空间差异。发现无机氮（NH、NO、NO）水平是控制 n-damo 活性和细菌群落组成的关键环境因素。总的来说，我们的研究结果表明了河流沉积物中 n-damo 细菌活性和群落结构的空间变化和环境调控，这扩展了我们对 n-damo 在河流系统中甲烷氧化和反应性氮去除中的定量重要性的理解。
