为挖掘到具备多种植物促生功能的益生菌株，对盐碱土中苜蓿（Medicago sativa Linn.）的根内部、根际土及根周土的可培养细菌进行了分离和鉴定，对无机磷溶解能力、固氮能力和耐盐性均突出的优选根瘤菌菌株进行形态观察、系统分类学鉴定以及生理生化功能和植物促生能力分析。结果表明：共分离鉴定出215株细菌，其中，芽孢杆菌门（Bacillota）和假单胞菌门（Pseudomonadota）占比较高，分别为63.7%和31.6%。分离得到的6株根瘤菌属（Rhizobium）细菌均为斯凯尔涅维采根瘤菌（Rhizobium skierniewicense），其中4株来自根内部，2株来自根际土。优选菌株CNBG-PGPR-28具有一定的耐盐性，并具备自生固氮与无机磷溶解能力，还具有多种生理生化功能，能够代谢甘油、D-阿拉伯糖等37种可发酵糖类化合物，并具有碱性磷酸盐酶、酯酶等9种生物酶活性。促生实验结果显示：CNBG-PGPR-28对盐碱土中的苜蓿（宿主）及栽培土中的生菜（Lactuca sativa var. ramosa Hort.）（非宿主）均具有促生作用，且对生菜的促生作用极显著（P＜0.01）。综上所述，盐碱土中苜蓿的根系微环境细菌种类丰富，芽孢杆菌门为绝对优势菌群；斯凯尔涅维采根瘤菌与苜蓿呈现内共生关系，其中，CNBG-PGPR-28不仅对盐碱土中的苜蓿具有促生能力，更是具备广谱应用潜力的多功能促生菌株。

To screen plant-beneficial strains with multiple growth-promoting functions, the culturable bacteria from the root interior, rhizosphere soil, and bulk soil of Medicago sativa Linn. in saline-alkali soil were isolated and identified, and morphological observation, systematic taxonomic identification, and analyses of physiological and biochemical functions and plant growth-promoting abilities were conducted for the superior rhizobial strain, which exhibited outstanding inorganic phosphorus solubilization capacity, nitrogen fixation capacity, and salt tolerance. The results show that a total of 215 bacterial strains are isolated and identified, among which, the proportions of Bacillota and Pseudomonadota are relatively high, accounting for 63.7% and 31.6%, respectively. The six bacterial strains belonging to Rhizobium are isolated, and all of them are identified as Rhizobium skierniewicense, among which four strains originate from the root interior and two strains originate from the rhizosphere soil. Superior strain CNBG-PGPR-28 exhibits a certain degree of salt tolerance, and possesses free-living nitrogen fixation and inorganic phosphorus solubilization capacities. It also demonstrates multiple physiological and biochemical functions, capable of metabolizing 37 fermentable carbohydrates such as glycerol and D-arabinose and exhibiting 9 enzyme activities such as alkaline phosphatase and esterase. The growth promotion experiments indicate that CNBG-PGPR-28 exhibits growth-promoting effects on M. sativa (host) in saline-alkali soil and Lactuca sativa var. ramosa Hort. (non-host) in cultivated soil, and has a extremely significant (P<0.01) growth-promoting effect on L. sativa var. ramosa. In conclusion, the bacterial species in the root microenvironment of M. sativa in saline-alkali soil are abundant, and Bacillota is the absolutely dominant phylum; R. skierniewicense exhibits an endosymbiotic relationship with M. sativa, among which, CNBG-PGPR-28 not only possesses growth-promoting capacity on M. sativa in salinealkali soil, but also represents a multifunctional growth-promoting strain with broad-spectrum application potential.