Heavy metals in soil, as selective agents, can change the structure of plant-associated bacterial communities and their metabolic properties, leading to the selection of the most-adapted strains, which might be useful in phytoremediation. Trifolium repens, a heavy metal excluder, naturally occurs on metal mine waste heaps in southern Poland characterized by high total metal concentrations. The purpose of the present study was to assess the effects of toxic metals on the diversity and metabolic properties of the microbial communities in rhizospheric soil and vegetative tissues of T. repens growing on three 70–100-years old Zn–Pb mine waste heaps in comparison to Trifolium-associated bacteria from a non-polluted reference site. In total, 113 cultivable strains were isolated and used for 16S rRNA gene Sanger sequencing in order to determine their genetic affiliation and for in vitro testing of their plant growth promotion traits. Taxa richness and phenotypic diversity in communities of metalliferous origin were significantly lower (p < 0.0001) compared to those from the reference site. Two strains, Bacillus megaterium BolR EW3_A03 and Stenotrophomonas maltophilia BolN EW3_B03, isolated from a Zn–Pb mine waste heap which tested positive for all examined plant growth promoting traits and which showed co-tolerance to Zn, Cu, Cd, and Pb can be considered as potential facilitators of phytostabilization.

中文翻译：

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白三叶草相关细菌是促进锌和铅污染的废物堆植物稳定的潜在工具。

土壤中的重金属作为选择剂，可以改变植物相关细菌群落的结构及其代谢特性，从而导致选择最适合的菌株，这可能在植物修复中有用。白三叶草，一种重金属排除物，自然存在于波兰南部的金属矿山废料堆中，其特征是总金属浓度高。本研究的目的是评估的多样性和根际土壤和植物组织中的微生物群落的代谢特性有毒金属的影响白三叶草增长的三个70-100-岁锌-铅废矿堆在与三叶草比较来自无污染参考位点的细菌。总共分离出113种可培养菌株，并用于16S rRNA基因Sanger测序，以确定它们的遗传隶属关系并用于体外测试其植物生长促进性状。与参考地点相比，含金属来源的群落中的分类单元丰富度和表型多样性显着较低（p <0.0001）。从Zn-Pb矿山废料堆中分离出的两个菌株，巨型芽孢杆菌BolR EW3_A03和嗜麦芽嗜麦芽单胞菌BolN EW3_B03，对所有检测到的植物生长促进性状均呈阳性，并显示对Zn，Cu，Cd和Pb的共耐受作为植物稳定作用的潜在促进剂。