Abstract: In order to screen out resistant rhizobial strains which could tolerate complex heavy metals and could colonize and coexist in the roots of native leguminous plants,nodule samples of wild legume herbage were collected from manganese mining areas and lead-zinc ore areas in Guizhou Province. Bacteria were isolated and purified. The bacterial morphology was observed and 16S rRNA genes were analyzed by sequencing. A total of 71 rhizobium strains were obtained and preserved. The results of the phylogenetic and floristic analysis showed that all the identified rhizobial strains belonged to 7 genera and 28 species,of which Rhizobium was the dominant genera and R.indigoferae was the dominant species,with the distribution frequencies of 54.93% and 15.49%,respectively. Seventeen rhizobial strains of different species from different tailings areas were selected,and by using the heavy metal plate method,all the strains’ tolerance to five heavy metals widely distributed in Guizhou tailings soil,including Pb²⁺,Zn²⁺,Cr⁶⁺,Mn^2+, and Cd²⁺,were determined. Test results indicated that 17 strains all harbored different levels of resistant ability to three or more than three heavy metals,among which HMZT039-6,HSST042-6,HSST042-1,ZHQT052-1,and HXTT050-1 took on endurance capacity to all five kinds of heavy metal ions,and they were the optimal resistant rhizobial strains screened out. The results of this study could provide symbiotic microbial resources for the remediation and treatment of soil heavy metal pollution in the local regions.

Key words: Guizhou tailings area, Natural legume grass, Symbiotic rhizobia, Resistant strains, Heavy metal pollution remediation

摘要： 为了筛选获得对复合重金属具有耐受能力且能在本地豆科植物根系内定殖共生的抗性根瘤菌，本研究从贵州省内的锰矿区、铅锌矿区采集野生豆科牧草根瘤样品，经分离纯化、菌体形态观察、16S rRNA基因序列比对分析，获得71个根瘤菌保存菌株。系统发育和区系分析结果表明，分离菌株分属7属28种，其中根瘤菌属(Rhizobium)的分布频率高达54.93%，为优势属，木兰根瘤菌(R.indigoferae)的分布频率最高(15.49%)，为优势种。选择来自不同尾矿区、不同种类的根瘤菌17株，采用重金属平板法测定各供试菌株对贵州尾矿土分布较多的Pb²⁺，Zn²⁺，Cr⁶⁺，Mn²⁺，Cd²⁺五种重金属的耐受性，结果发现17个菌株对3种或3种以上的重金属都具有不同程度的耐受能力，其中HMZT039-6，HSST042-6，HSST042-1，ZHQT052-1和HXTT050-1对5种重金属离子均有耐受能力，为筛选出的最优抗性根瘤菌株。本研究结果可为本地区土壤重金属污染的修复治理提供共生微生物资源。

关键词: 贵州尾矿区, 天然豆科牧草, 共生根瘤菌, 抗性菌株, 重金属污染修复