异化硝酸盐还原成铵(DNRA)是淡水沉积物中重要的硝酸盐还原途径。许多研究都集中在各种自然栖息地的DNRA过程上。然而,梯级水库的联合运行将影响沉积物的物理和化学性质,这可能会改变级联水库表层沉积物中的DNRA过程和细菌群落模式。我们的研究是第一个调查潜在DNRA率的时空分布模式,nrfA基因丰度,澜沧江梯级水库表层沉积物中的DNRA细菌群落多样性。浆液培养实验结合15N同位素示踪实验确定DNRA的潜在速率为0.01-0.15nmol·Ncm-3h-1,qPCR结果表明nrfA的丰度范围为1.08×105-2.51×106拷贝g-1干重。nrfA基因的高通量测序显示,厌氧细菌的相对丰度(平均4.52%),Polyangium(4.09%),铀(1.86%),Geobacter(1.34%),腔隙(1.32%)高。Pearson和RDA相关分析显示nrfA基因丰度与海拔呈正相关,pH值,OC,和沙子浓度。厌氧细菌与储层年龄和DNRA潜力率呈正相关。确定性环境选择过程在DNRA细菌群落的形成中起着至关重要的作用。网络分析显示,优势DNRA属是澜沧江梯级水库沉积物中DNRA微生物群落的关键种群。这项研究表明,DNRA细菌活性和群落结构的变化在很大程度上是由级联水库的建设驱动的,为进一步认识梯级水库生态系统DNRA群落特征提供了新思路。
Dissimilatory nitrate reduction to ammonium (DNRA) is an important nitrate reduction pathway in freshwater sediments. Many studies have focused on the DNRA process in various natural habitats. However, the joint operation of cascade reservoirs will affect the physical and chemical properties of sediments, which may change the DNRA process and bacterial community pattern in the surface sediments of cascade reservoirs. Our study was the first to investigate the spatiotemporal distribution patterns of potential DNRA rate, nrfA gene abundances, and DNRA bacterial community diversity in surface sediments of the Lancang River cascade reservoirs. The results of slurry incubation experiments combined with the 15N isotope tracer experiment ascertained that the potential rates of DNRA were 0.01-0.15 nmol-N cm-3 h-1, and qPCR results indicated that the abundance range of nrfA was 1.08 × 105-2.51 × 106 copies g-1 dry weight. High throughput sequencing of the nrfA gene revealed that the relative abundance of Anaeromyxobacter (4.52% on average), Polyangium (4.09%), Archangium (1.86%), Geobacter (1.34%), and Lacunisphaera (1.32%) were high. Pearson and RDA correlation analysis exhibited that nrfA gene abundance was positively correlated with altitude, pH, OC, and sand concentration. Anaeromyxobacter was positively correlated with reservoir age and DNRA potential rate. The deterministic environmental selection process plays a crucial role in the formation of the DNRA bacterial community. Network analysis displayed that the dominant DNRA genus was the key population of the DNRA microbial community in the sediments of Lancang River cascade reservoirs. This study reveals that the variation of DNRA bacterial activity and community structure is largely driven by the construction of cascade reservoirs, and provides a new idea for further understanding the characteristics of the DNRA community in the cascade reservoir ecosystem.