荒漠植物根际促生菌的筛选、鉴定及功能特性

Isolation, identification, and functional characterization of plant growth-promoting rhizobacteria associated with desert plants

摘要:

目的 挖掘适用于盐碱地生态修复的微生物资源，明确其抗逆性和促生特性，以期为基于生物技术的农业可持续发展提供理论依据。方法 以甘肃省民勤绿洲的3种典型盐生植物——多枝柽柳(Tamarix ramosissima)、黑果枸杞(Lycium ruthenicum)和盐爪爪(Kalidium foliatum)为研究对象，从其根际土壤中分离和筛选植物根际促生菌(plant growth-promoting rhizobacteria, PGPR)，并通过16S rRNA基因序列分析对优良菌株进行鉴定，系统评价其固氮、溶磷、分泌吲哚-3-乙酸(indole-3-acetic acid, IAA)、胞外多糖(exopolysaccharides, EPS)和铁载体的能力，以及耐盐、耐旱、酸碱适应性、温度适应性和对6种常见植物病原真菌的拮抗作用。结果 共分离获得62株细菌，从中筛选出7株多功能PGPR (HL3、HL6、HL12、HG3、HG8、HG12和HG24)，分别鉴定为线状普里斯特氏菌(Priestia filamentosa)、萎缩芽孢杆菌(Bacillus atrophaeus)、内生泛菌(Pantoea endophytica)、耐寒近芽孢杆菌(Peribacillus frigoritolerans)、阿氏芽胞杆菌(Bacillus aryabhattai)、枯草芽孢杆菌粪便亚种(Bacillus subtilis subsp. stercoris)和皮尔瑞俄类芽孢杆菌(Paenibacillus peoriae)。筛选的菌株均兼具至少2种促生特性；其中HL6和HG24同时具备固氮、溶磷、产IAA、EPS和铁载体的能力。抗逆性评价表明，HL3和HL6可耐受12% NaCl，HL3和HG8可耐受-20 bar渗透胁迫；多数菌株适应pH 9.0及28-45 ℃温度范围。拮抗试验显示，HL6对全部6种病原真菌均有抑制作用，HG24对5种病原真菌具有广谱拮抗活性，二者对茄链格孢菌(Alternaria solani)抑菌效果最强。结论 本研究从干旱区盐生植物根际筛选获得的PGPR兼具显著促生与抗逆特性，可为盐碱地生物修复及本地化微生物菌剂的开发提供重要微生物资源支撑。

Abstract:

Objective To explore microbial resources suitable for the ecological restoration of saline-alkaline soils and elucidate their stress tolerance and plant growth-promoting traits, thereby providing a theoretical basis for biotechnology-driven sustainable agricultural development.Methods Plant growth-promoting rhizobacteria (PGPR) were isolated and screened from the rhizosphere soils of three representative halophytes—Tamarix ramosissima, Lycium ruthenicum, and Kalidium foliatum—growing in the Minqin Oasis, Gansu Province, northwestern China. Selected strains were taxonomically identified by 16S rRNA gene sequence analysis. Their functional traits were systematically evaluated, including nitrogen fixation, phosphate solubilization, and production of indole-3-acetic acid (IAA), exopolysaccharides (EPS), and siderophores. In addition, stress tolerance under salinity, drought, pH, and temperature gradients, as well as antagonistic activity against six common phytopathogenic fungi, was assessed.Results A total of 62 bacterial isolates were obtained, among which seven multifunctional PGPR strains (HL3, HL6, HL12, HG3, HG8, HG12, and HG24) were selected and identified as Priestia filamentosa, Bacillus atrophaeus, Pantoea endophytica, Peribacillus frigoritolerans, Bacillus aryabhattai, Bacillus subtilis subsp. stercoris, and Paenibacillus peoriae, respectively. All the selected strains exhibited at least two plant growth-promoting traits. Notably, strains HL6 and HG24 simultaneously possessed nitrogen-fixing ability, phosphate-solubilizing capacity, and the ability to produce IAA, EPS and siderophores, showcasing pronounced multifunctionality. Stress tolerance assays showed that strains HL3 and HL6 tolerated up to 12% NaCl, while HL3 and HG8 withstood osmotic stress equivalent to -20 bar. Most strains remained active under alkaline conditions (pH 9.0) and within a temperature range of 28-45 ℃. Antagonistic assays revealed that HL6 inhibited all six tested phytopathogenic fungi, and HG24 exhibited broad-spectrum antagonistic activity against five pathogens, with the strongest inhibition observed against Alternaria solani.Conclusion This study demonstrates that PGPR isolated from the rhizosphere of halophytes in arid regions possess diverse plant growth-promoting functions and strong stress tolerance. These multifunctional and resilient strains represent valuable microbial resources for saline-alkaline soil remediation and the development of locally adapted biofertilizers, contributing to sustainable agriculture and ecological restoration in arid environments.