Abstract: The study aimed to obtain multi-functional plant growth promoting rhizobacteria (PGPR) and clarify theirphysiological and biochemical characteristics,including nitrogenfixation,phosphorusand potassium solubilization, rhizosphere soil and roots from five widely distributed alpine meadow plants were used to isolate the bacterial strains,and a total of 44 strains were obtained. The results showed that 25 strains were inorganic-phosphorus-dissolving ones and 24 strains were organic-phosphorus-dissolving ones, the capacities of phosphorus-dissolving for these two strain types were 10.98～90.27 μg·mL^-1 and 10.58～64.56 μg·mL^-1,respectively; Additionally,20 strains were able to fix nitrogen biologically nitrogenase activity:5.23～64.87 nmol (C₂H₄)·h^-1·mL^-1 and 21 strains were able to release potassium (potassium releasing capacity:9.23～73.21 μg·mL^-1). On basis of morphological,physiological and biochemical characteristics,12 strains with multiple functions (phosphorus-solubilizing,nitrogen-fixing and potassium-releasing) were finally screened out. These 12 strains were identified as Acinetobacter,Serratia,Pseudomoas,Bacillus,Delftia and Stenotrophomonas with molecular method.The study provides a good reference for developing high quality soil microbial fertilizers in the northwestern Sichuan Plateau.

Key words: Alpine meadow, Plant growth-promoting rhizobacteria (PGPR), Screening strains, Physiological and biochemical characteristics

摘要： 为获得多功能的高寒植物根际促生菌（Plant growth-promoting rhizobacteria，PGPR），并明确其生理生化特性，本研究采用选择性培养基法从川西北广泛分布的5种高寒草甸植物根际土壤和根系中分离了44株菌株，并对菌株的溶磷、固氮和解钾特性进行测定。结果显示：25株为溶无机磷菌株，24株为溶有机磷菌株，溶磷量分别在10.98～90.27 μg·mL^-1和10.58～64.56 μg·mL^-1之间；固氮菌株共20株，其固氮酶活性介于5.23～64.87 nmol（C₂H₄）·h^-1·mL^-1之间；解钾菌株21株，解钾量在9.23～73.21 μg·mL^-1之间。经过形态学和生理生化特征分析，最终筛选出12株兼具溶磷、固氮和解钾的多功能菌株，分子鉴定将其归属于不动杆菌属（Acinetobacter）、沙雷氏菌属（Serratia）、假单胞菌属（Pseudomoas）、芽孢杆菌属（Bacillus）、戴尔福特菌属（Delftia）和寡养单胞菌属（Stenotrophomonas）。研究结果可为川西北高原土壤微生物菌肥的开发提供优质菌源参考。

关键词: 高寒草甸, 根际促生菌, 菌株筛选, 生理生化特性