中文摘要：

调查了南京栖霞铅锌银矿区龙葵根际土壤和植株的重金属含量,采用稀释培养法和选择性培养基分离筛选Cd抗性细菌并研究其生物学特性。结果表明,栖霞山铅锌银矿区龙葵根际土壤总Cd含量平均为19.74 mg.kg-1,污染十分严重,龙葵（Solanum nigrum）茎和叶的Cd富集系数分别为1.21～9.65和0.65～4.76,对Cd具有较强富集能力。从龙葵根际土壤和植株中分离筛选到5株Cd抗性细菌,菌株AR1和AY1分别分离自根和叶内,BGJ4和CGJ1均分离自根际土。16S rDNA序列分析表明5株Cd抗性细菌均属于芽孢杆菌属（Bacillus）,能够产生吲哚乙酸（IAA）和铁载体,根内生细菌AR1在含Cd2＋30 mg.L-1的培养基中仍能生长良好。在1.5 mg.L-1Cd2＋污染条件下,Cd抗性细菌AR1、AY1、BGJ4菌株能够明显促进油菜（Oilseed rape）幼苗根的伸长,在植物-微生物联合修复重金属污染土壤方面具有潜在的应用前景。

英文摘要：

Concentrations of Cd in the plant of Solanum nigrum and in the rhizospheric soil of the plant growing in the Nanjing Qixia Pb-Zn Mine Area were determined,and Cd-resistant endophytic and rhizobacteria were isolated from the plant and characterized with respect to heavy metal resistance and production of plant growth-promoting factors.Results show that the soil was seriously polluted by Cd,with total Cd content averaging 19.74 mg·kg-1.The Cd bioaccumulation coefficient of the stem and leaf of the plant was 1.21-9.65 and 0.65-4.76,respectively,which suggests that the plant is highly capable of enriching Cd.A total of five Cd-resistant strains of bacteria were isolated from the plant and the rhizospheric soil of the plant,Strain AR1 from the root,Strain AY1 from the leaf and Strains BGJ4 and CGJ1 from the rhizospheric soil.Phylogenetic analysis based on 16S rDNA sequencing reveals that the 5 Cd-resistant strains all belonged to the genus of Bacillus,capable of producing IAA and iron carriers.Strain AR1 could even survive and grow well in the medium containing 30 mg·L-1 of Cd2＋.Rapeseed plants growing in vermiculite containing 1.5 mg·L-1 of Cd2＋,were found to increase roots growth after inoculation with the isolates AR1,AY1,and BGJ4.All the findings indicate that Cd-resistant bacteria producing IAA and siderophores in S.nigrum may be used for plant growth promotion and bacteria-assisted phytoremediation of heavy metal-contaminated soil.