Although previous studies have shown that nitrogen (N) fertilization may negatively affect bacterial diversity in bulk soil, information regarding N impacts on the microbial structure and function of both the bulk and rhizosphere soil bacterial microbiome (bacteriome) is less abundant. In this study, tomato and common bean plants, two globally important vegetable crops, were grown in soils fertilized with urea, ammonium, or nitrate for four consecutive fruit harvests. 16S rRNA gene amplicon sequencing and 16S rRNA gene-predicted functional analyses were performed on bulk and rhizosphere soil samples. Correlation analyses were used to examine the links between changes in the composition, structure, and predicted functionality of the bulk and rhizosphere soil bacteriome with variations in soil properties. All of the tested N-fertilizers decreased the bacterial richness and altered community composition and predicted functionality of the bulk and rhizosphere soil bacteriome of both plants. The magnitude of these effects was dependent on the soil component (bulk and rhizosphere) and type of N-fertilizer and was controlled by the N and C soil content. For both plants, decreases in bacterial diversity due to N-fertilizers were more pronounced in the rhizosphere than in bulk soils and higher in the fourth than first harvest. These results suggest that the recruitment of bacteria by plants is affected by N-fertilization. The present findings should facilitate expanded studies to identify soil-plant-microbiome interactions in N-treated soils with potential consequences for plant growth in agricultural systems.

尽管以前的研究表明，氮肥可能会对散装土壤中的细菌多样性产生不利影响，但是有关氮对散装和根际土壤细菌微生物组（细菌组）微生物结构和功能的影响的信息较少。在这项研究中，番茄和普通豆类植物（两种全球重要的蔬菜作物）在施以尿素，铵盐或硝酸盐的土壤中连续生长了四个果实。在大量和根际土壤样品上进行了16S rRNA基因扩增子测序和16S rRNA基因预测的功能分析。相关分析被用来检查土壤中细菌和根际土壤细菌组成，结构和预测功能的变化之间的联系，以及土壤性质的变化。所有测试的氮肥均降低了两种植物的细菌富集度，改变了群落组成，并预测了其主体和根际土壤细菌组的功能。这些影响的程度取决于土壤成分（大块和根际）和氮肥的类型，并受氮和碳含量的控制。对于这两种植物，根际土壤中氮肥导致的细菌多样性下降比散土中更为明显，第四季度比第一次收获时更高。这些结果表明，植物对细菌的募集受到氮肥的影响。本研究结果应有助于扩大研究范围，以鉴定经过N处理的土壤中土壤与植物之间的微生物组相互作用，这些相互作用对农业系统中植物的生长具有潜在的影响。