Ouyang Yang, Norton Jeanette M
Department of Plants, Soils and Climate, Utah State University, Logan, UT, United States.
Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, United States.
Front Microbiol. 2020 Aug 4;11:1736. doi: 10.3389/fmicb.2020.01736. eCollection 2020.
Autotrophic nitrification is mediated by ammonia oxidizing bacteria (AOB) or ammonia oxidizing archaea (AOA) and nitrite oxidizing bacteria (NOB). Mounting studies have examined the impact of nitrogen (N) fertilization on the dynamic and diversity of AOA and AOB, while we have limited information on the response of the activity, abundance, and diversity of NOB to N fertilization. We investigated the influence of organic and inorganic N fertilizers on soil NOB in silage corn field plots that received contrasting nitrogen (N) treatments: control (no additional N), ammonium sulfate (AS 100 and 200 kg N ha), and compost (200 kg N ha). Nitrifying community was examined using a universal marker (16S rRNA gene), functional gene markers (AOB and ), and metagenomics. The overall nitrifying community was not altered after the first fertilization but was significantly shifted by 4-year repeated application of ammonium fertilizers. were the dominant NOB (>99.7%) in our agricultural soil. Both community compositions of AOB and were significantly changed by ammonium fertilizers but not by compost after 4 years of repeated applications. All nitrifiers, including comammox, were recovered in soil metagenomes based on a gene-targeted assembly, but their sequence counts were very low. Although N treatment did not affect the abundance of determined by real-time quantitative PCR, ammonium fertilizers significantly promoted rates of potential nitrite oxidation determined at 0.15 mM nitrite in soil slurries. Understanding the response of both ammonia oxidizers and nitrite oxidizers to N fertilization may initiate or improve strategies for mitigating potential environmental impacts of nitrate production in agricultural ecosystems.
自养硝化作用由氨氧化细菌（AOB）、氨氧化古菌（AOA）和亚硝酸盐氧化细菌（NOB）介导。越来越多的研究探讨了氮肥对AOA和AOB动态及多样性的影响，而关于NOB的活性、丰度和多样性对氮肥响应的信息却很有限。我们研究了有机和无机氮肥对青贮玉米田土壤中NOB的影响，该田块接受了不同的氮（N）处理：对照（不额外施氮）、硫酸铵（AS 100和200 kg N/ha）以及堆肥（200 kg N/ha）。使用通用标记（16S rRNA基因）、功能基因标记（AOB和）以及宏基因组学对硝化群落进行了检测。首次施肥后，整个硝化群落没有改变，但4年重复施用铵肥后发生了显著变化。在我们的农业土壤中，硝化螺旋菌属是主要的NOB（>99.7%）。4年重复施用后，铵肥显著改变了AOB和硝化螺旋菌属的群落组成，但堆肥没有。基于基因靶向组装，在土壤宏基因组中发现了所有硝化菌，包括完全氨氧化菌，但它们的序列数非常低。尽管氮处理不影响通过实时定量PCR测定的硝化螺旋菌属丰度，但铵肥显著提高了在土壤泥浆中0.15 mM亚硝酸盐条件下测定的潜在亚硝酸盐氧化速率。了解氨氧化菌和亚硝酸盐氧化菌对氮肥的响应，可能会启动或改进减轻农业生态系统中硝酸盐生产潜在环境影响的策略。
