title: Assessment of bacterial communities and characterization of lead-resistant bacteria in the rhizosphere soils of metal-tolerant Chenopodium ambrosioides grown on lead-zinc mine tailings.
abstract: Bacterial communities in the rhizosphere soils of metal tolerant and accumulating Chenopodium ambrosioides grown in highly and moderately lead-zinc mine tailings contaminated-soils as well as the adjacent soils with low metal contamination were characterized by using cultivation-independent and cultivation techniques. A total of 69, 73, and 83 bacterial operational taxonomic units (OTUs) having 84.8-100% similarity with the closest match in the database were detected among high, moderate, and low-contamination soil clone libraries, respectively. These OTUs had a Shannon diversity index value in the range of 4.06-4.30. There were 9, 10, and 14 bacterial genera specific to high, moderate, and low metal-contaminated soil clone libraries, respectively. Phylogenetic analysis showed that the Pb-resistant isolates belonged to 8 genera. Pseudomonas and Arthrobacter were predominant among the isolates. Most of the isolates (82-86%) produced indole acetic acid and siderophores. More strains from the highly metal-contaminated soil produced 1-aminocyclopropane-1-carboxylate deaminase than the strains from the moderately and lowly metal-contaminated soils. In experiments involving canola grown in quartz sand containing 200 mg kg(-1) of Pb, inoculation with the isolated Paenibacillus jamilae HTb8 and Pseudomonas sp. GTa5 was found to significantly increase the above-ground tissues dry weight (ranging from 19% to 36%) and Pb uptake (ranging from 30% to 40%) compared to the uninoculated control. These results show that C. ambrosioides harbor different metal-resistant bacterial communities in their rhizosphere soils and the isolates expressing plant growth promoting traits may be exploited for improving the phytoextraction efficiency of Pb-polluted environment.
authors.affiliation: Key Laboratory of Agricultural Environment Microbiology, Ministry of Agriculture, College of Life Science, Nanjing Agricultural University, Nanjing 210095, PR China.
authors.forename: Wen-hui
authors.initials: WH
authors.lastname: Zhang
authors.forename: Zhi
authors.initials: Z
authors.lastname: Huang
authors.forename: Lin-yan
authors.initials: LY
authors.lastname: He
authors.forename: Xia-fang
authors.initials: XF
authors.lastname: Sheng
mesh_terms: D001419:Bacteria / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D029741:Brassica rapa / Q000254:growth & development* / Q000378:metabolism* / Q000382:microbiology; D019755:Carbon-Carbon Lyases / Q000737:chemistry / Q000494:pharmacology; D027464:Chenopodium ambrosioides / Q000254:growth & development* / Q000378:metabolism* / Q000382:microbiology; D002681:China; D015169:Colony Count, Microbial; D007210:Indoleacetic Acids / Q000378:metabolism; D007854:Lead / Q000378:metabolism / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D058441:Rhizosphere; D017262:Siderophores / Q000378:metabolism; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D007210:Indoleacetic Acids; D012336:RNA, Ribosomal, 16S; D017262:Siderophores; D012989:Soil Pollutants; D007854:Lead; C030737:indoleacetic acid; C033634:1-aminocyclopropane-1-carboxylate deaminase; D019755:Carbon-Carbon Lyases