Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
Environ Res. 2020 Jul;186:109612. doi: 10.1016/j.envres.2020.109612. Epub 2020 May 1.
Nitrate (NO) reduction partitioning between denitrification, anaerobic ammonium oxidation (anammox), denitrifying anaerobic methane oxidation (DAMO), and dissimilatory nitrate reduction to ammonium (DNRA), can influence the nitrogen (N) use efficiency and crop production in arid farmland. The microbial structure, function and potential rates of denitrification, anammox, DAMO and DNRA, and their respective contributions to total NO reduction were investigated in rhizosphere and non-rhizosphere soil of four typical crops in north China by functional gene amplification, high-throughput sequencing, network analysis and isotopic tracing technique. The measured denitrification and DNRA rate varied from 0.0294 to 20.769 nmol N g hand 2.4125-58.682 nmol N g h, respectively, based on which DNRA pathway contributed to 84.44 ± 14.40% of dissimilatory NO reduction, hence dominated NO reduction processes compared to denitrification. Anammox and DAMO were not detected. High-throughput sequencing analysis on DNRA nrfA gene, and denitrification nirS and nirK genes demonstrated that these two processes did not correlate to corresponding gene abundance or dominant genus. RDA and Pearson's correlation analysis illustrated that DNRA rate was significantly correlated with the abundance of Chthiniobacter, as well as total organic matter (TOM); denitrification rate was significantly correlated with the abundance of Lautropia, so did TOM. Network analysis showed that the genus performed DNRA was the key connector in the microbial community of dissimilatory nitrate reducers. This study simultaneously investigated the dissimilatory nitrate reduction processes in rhizosphere and non-rhizosphere soils in arid farmland, highlighting that DNRA dominated NO reduction processes against denitrification. As denitrification results in N loss, whereas DNRA contributes to N retention, the relative contributions of DNRA versus denitrification activities should be considered appropriately when assessing N transformation processes and N fertilizer management in arid farmland fields.
硝酸盐（NO）还原在反硝化、厌氧氨氧化（anammox）、反硝化厌氧甲烷氧化（DAMO）和异化硝酸盐还原为铵（DNRA）之间的分配，会影响干旱农田的氮（N）利用效率和作物产量。本研究通过功能基因扩增、高通量测序、网络分析和同位素示踪技术，研究了中国北方四种典型作物根际和非根际土壤中反硝化、anammox、DAMO 和 DNRA 的微生物结构、功能和潜在速率及其对总 NO 还原的贡献。根据测量的反硝化和 DNRA 速率（0.0294-20.769 nmol N g h 和 2.4125-58.682 nmol N g h），DNRA 途径贡献了 84.44±14.40%的异化 NO 还原，因此与反硝化相比，DNRA 途径主导了 NO 还原过程。未检测到 anammox 和 DAMO。DNRA nrfA 基因和反硝化 nirS 和 nirK 基因的高通量测序分析表明，这两个过程与相应基因丰度或优势属没有相关性。RDA 和 Pearson 相关性分析表明，DNRA 速率与 Chthiniobacter 和总有机物质（TOM）的丰度显著相关；反硝化速率与 Lautropia 的丰度显著相关，TOM 也是如此。网络分析表明，进行 DNRA 的属是异化硝酸盐还原菌微生物群落的关键连接体。本研究同时调查了干旱农田根际和非根际土壤中的异化硝酸盐还原过程，强调了 DNRA 对反硝化的主导作用。由于反硝化导致 N 损失，而 DNRA 有助于 N 保留，因此在评估干旱农田中氮转化过程和氮肥管理时，应适当考虑 DNRA 与反硝化活性的相对贡献。
