【背景】紫花苜蓿是优良的豆科牧草，可以与丛枝菌根(Arbuscular mycorrhizae，AM)真菌和根瘤菌形成共生关系，接种AM真菌和根瘤菌可以促进土壤氮、磷循环以及提高苜蓿产量。【目的】探究接种AM真菌和根瘤菌对苜蓿根际细菌群落结构和功能的影响。【方法】采集6个不同处理组苜蓿根际、非根际土壤样品，基于细菌16S rRNA基因V3?V4区进行高通量测序，分析比较不同处理组苜蓿根际、非根际土壤中细菌群落分布的规律，并采用PICRUSt软件对不同处理组间菌群功能进行预测。【结果】36个土壤样品中共检测到3 849个OTU，分属于50门59纲132目249科595属398种。其中主要的优势菌门为Proteobacteria (52.81%?81.46%)、Bacteroidetes (7.83%?19.68%)及Actinobacteria (2.21%?16.4%)。与不接种相比，接种根内球囊霉和摩西球囊霉分别提高了Gammaproteobacteria和Bacteroidia有益菌的丰度，接种根瘤菌提高了固氮菌(Alphaproteobacteria)的丰度。PICRUSt功能预测表明，细菌菌群共有35个子功能，菌群功能丰富，代谢为最主要的功能，并且接种根瘤菌可增加氨基酸代谢，从而有利于植株N素循环，而接种AM真菌可能对于N循环有一定的抑制作用，相比于单接种AM真菌，双接种AM真菌和根瘤菌处理组碳水化合物代谢更强，从而更有益于植株的氮、磷循环。【结论】接种AM真菌和根瘤菌可分别提高苜蓿根系与氮、磷循环有关的不同有益菌的丰度，从而更有益于植株的氮、磷循环，该结果为提高植株养分吸收、提高苜蓿产量以及菌肥开发利用提供了科学依据。
[Background] Medicago sativa is excellent leguminous forage that can reciprocate with arbuscular mycorrhizal (AM) fungi and rhizobium. Inoculation of AM fungi and rhizobium can promote soil nitrogen and phosphorus cycling and increase alfalfa yield. [Objective] To study the effects of AM fungi and Rhizobium on the structure and function of rhizosphere bacterial community. [Methods] Rhizosphere and non-rhizosphere soil samples of six different treatment groups were collected, based on the high-throughput sequencing technology of bacterial 16S rRNA gene V3?V4 region. The bacterial diversity and community distribution in the rhizosphere and non-rhizosphere soils of different inoculation treatment groups were analyzed and compared. PICRUSt software was applied to predict the function of bacterial microbiota between different treatment groups. [Results] A total of 3 849 OTU were obtained from 36 soil samples, belonging to 398 species of 50 divisions, 59 classes, 132 orders, 249 families and 595 genera. The main dominant bacteria were Proteobacteria (66.79%, 52.81%?81.46%), Bacteroidetes (7.83%?19.68%) and Actinobacteria (2.21%?16.40%). Compared with no inoculation, the inoculation treatment of Glomus intraradices and G. mosseae increased the beneficial bacteria of Gammaproteobacteria and Bacteroidia, inoculation with Rhizobium increased the abundance of the nitrogen-fixing bacteria Alphaproteobacteria. PICRUSt function prediction analysis indicateed that the bacterial microbiota had a total of 35 sub-functions. Inoculation with rhizobium can increase amino acid metabolism, which is conducive to plant N-nutrient cycle, and inoculation with AM fungi may have a certain inhibitory effect on N-cycle. Compared with single inoculation with AM fungi, double inoculation with AM fungi and rhizobium treatment group had stronger carbohydrate metabolism, which was more beneficial to plant nitrogen and phosphorus cycle. [Conclusion] The inoculation with AM fungi and rhizobium can increase the abundance of different beneficial bacteria related to nitrogen and phosphorus cycle in alfalfa, the results provide a scientific basis for plant nutrient uptake, the increase of alfalfa yield and the development and utilization of bacterial fertilizer.