The properties and roles of indigenous heavy metal-tolerant microbes have been extensively investigated for plant growth promotion and ecological remediation at contaminated sites,but these studies seldom address the community-level features of the microbes.Three soil samples were collected from the rhizosphere of a Cu-tolerant plant,Artemisia capillaries Thunb.,grown on a Cu mine spoil.The MiSeq high-throughput sequencing technique,targeting the V3-V4 region of the bacterial 16S rDNA gene,was used to investigate the bacterial community structure and analyze the links between the bacterial community and soil environmental parameters.The results showed that sampling site Cu3 contained higher concentrations of Cu and Zn than Cu1 and Cu2 did.The Shannon-Wiener diversity index,richness,evenness,ACE index,and Chao1 index of the bacterial communities in Cu3 were all lower than those of Cu1 and Cu2,but coverage by the bacterial communities in Cu3 was higher than that of Cu1.The top 10 dominant phyla of bacteria accounted for 95％ of the total relative abundance and 8 out of the top 10 dominant phyla were the same across all three sampling sites;these were Proteobacteria,Acidobacteria,Bacteroidetes,Gemmatimonadetes,Actinobacteria,Verrucomicrobia,Planctomycetes,and Unclassified.The relative abundances of Proteobacteria,Bacteroidetes,and Gemmatimonadetes were higher in Cu1 than in Cu2 and Cu3,but the opposite was true for Acidobacteria,Actinobacteria,Verrucomicrobia,Chloroflexi,and Unclassified phyla,indicating that different bacteria responded differently to Cu stress.The relative abundance of Chloroflexi,which only accounted for 0.54％ of the bacterial community in Cu1,was 4.54％ and 15.27％ in Cu2 and Cu3,respectively.Bacterial communities were clustered into three different groups,according to principal coordinates analysis (PCoA) and redundancy analysis (RDA).The variation in bacterial communities was controlled by 11 principal coordinates,among which the first and second coordinates explained 74.3％ and 14.8％ of the total variance,respectively.Soil environmental parameters were closely related to the differences in bacterial community and explained 97.5％ of the total variance.Total Cu,total P,pH,available P,and organic matter were the significant parameters;altogether,they accounted for 93.9％ of the total variance in bacterial community.Total Cu was the most powerful factor,and explained 60.6％ of the total variance independently.However,the dominant parameters differed across sampling sites.The RDA bioplots revealed that the bacterial community in Cu3,which showed the highest Cu tolerance,was positively related to total Cu.In contrast,the relatively Cu-sensitive bacterial community in Cu1 was positively correlated with pH and negatively correlated with total Cu.It is of vital importance to study how bacterial communities in the plant rhizosphere change with the environment and screen functional bacteria for plant-microbe remediation of heavy metal contamination.%采用MiSeq高通量测序技术对耐铜植物茵陈蒿根际的细菌16S rDNA基因V3-V4区片段进行了测序,研究了细菌群落结构的变化,并分析了其与土壤环境因子的关系.研究表明,采样点Cu3中细菌群落的多样性、丰富度、均匀度、ACE指数、Chao1指数等均显著低于Cu1和Cu2,但Cu3的覆盖度高于Cu1.排名前10的优势细菌门总相对丰度均在95％以上,其中8个优势细菌门在3个采样点中是相同的,包括Proteobacteria(变形菌门)、Acidobacteria(酸杆菌门)、Bacteroidetes(拟杆菌门)、Gemmatimonadetes(芽单胞菌门)、Actinobacteria(放线菌门)、Verrucomicrobia(疣微菌门)、Planctomycetes(浮霉菌门)和Unclassified(未分类门)等.采样点Cu1中变形菌门、拟杆菌门和芽单胞菌门的相对丰度显著高于其他两个采样点,而酸杆菌门、放线菌门、疣微菌门、绿弯菌门(Chloroflexi)和未分类门则刚好相反,表明细菌对胁迫环境的适应能力有明显差异.主坐标和冗余分析表明,3个采样点的细菌群落结构发生了明显改变.土壤环境因子与细菌群落的变化关系密切,8个因子的特征值共解释了97.5％的总方差.其中,总铜、总磷、pH、有效磷和有机质为显著性因子,可以解释93.9％的群落变化,但影响不同采样点细菌群落的主导因子有所差异.
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