Animal bodies are colonized by many microorganisms which can provide indispensable services to their hosts. Although nematode gut microbiota has been extensively studied in recent years, the driving factors of gut microbiome of soil nematodes from a long-term fertilization field are unclear. Here, using 16S rRNA gene amplicon sequencing, we explored the nematode gut microbiota under different fertilization patterns (control, inorganic fertilizers and mixed fertilizers) and fertilization durations (5 y, 8 y and 10 y). Our results revealed that nematode gut microbiota was dominated by core bacterial taxa AF502208 (anaerobic bacteria), Enterobacter (plant litter decomposition) and Ancylobacter (organic matter decomposition and nitrogen cycling), significantly distinct from soil microbiome, and the assembly of that was a non-random process, which suggested host conditions contributed to maintaining the gut microbiota. Moreover, fertilization pattern had a greater influence on nematode gut microbiome than fertilization duration. Inorganic fertilization (5.19) significantly reduced the diversity of the nematode gut microbiota (6.68) shown by Shannon index (P < 0.05). Canonical correspondence analysis demonstrates that soil properties such as pH, organic matter, total phosphorus, available phosphorus, ammonium nitrogen, moisture content, nitrate nitrogen and total nitrogen have significant effects on the nematode microbiome. Structured equation models further revealed that fertilization could obviously affect the nematode gut microbiota, and the effects were maintained even when accounting simultaneously for the drivers of soil bacteria and soil properties. This study provides a solid evidence that the shifting of nematode gut microbiota under long-term fertilization was resulted from environmental factors and host conditions, and advance the insights into host-microbiome in the agricultural ecosystems.

中文翻译：

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长期施肥下线虫肠道菌群的驱动因素

动物的身体被许多微生物所殖民，这些微生物可以为其宿主提供必不可少的服务。尽管近年来对线虫肠道菌群进行了广泛研究，但长期施肥领域中土壤线虫肠道菌群的驱动因素尚不清楚。在这里，我们使用16S rRNA基因扩增子序列，研究了不同施肥方式（对照，无机肥料和混合肥料）和施肥持续时间（5年，8年和10年）下的线虫肠道菌群。我们的结果表明，线虫肠道菌群主要由核心细菌类群AF502208（厌氧细菌），肠杆菌（植物凋落物分解）和弯曲杆菌控制。（有机物分解和氮循环）与土壤微生物组明显不同，并且其组装是非随机过程，这表明宿主条件有助于维持肠道菌群。此外，施肥方式对线虫肠道微生物组的影响大于施肥持续时间。香农指数（P）显示，无机肥（5.19）显着降低了线虫肠道菌群（6.68）的多样性。<0.05）。典型的对应分析表明，土壤特性（例如pH值，有机质，总磷，有效磷，铵态氮，水分，硝酸盐氮和总氮）对线虫微生物组具有重要影响。结构方程模型进一步表明，施肥可以明显影响线虫肠道菌群，即使同时考虑土壤细菌和土壤特性的驱动因素，其作用也得以保持。这项研究提供了有力的证据，表明长期受精后线虫肠道菌群的迁移是由环境因素和寄主条件引起的，并为深入了解农业生态系统中的寄主微生物组提供了见识。