Abstract The aim of this study was to investigate the extent of heavy metal (HM) pollution and its effect on microorganisms from rhizosphere soil in Baia Mare area (Maramureş County, Romania). Two sites with different contamination degrees were included in the study: one with a long history of mining activities and one within a drinking water safeguard zone. Rhizosphere soil samples were characterized with respect to physico-chemical parameters and the Cd, Cu, Pb and Zn contents. Native bacteria were investigated for HM tolerance and biofilm formation under toxic exposure by the microdilution assay. The most resistant strains were identified and the minimum inhibitory concentrations for HMs were determined. Cd, Cu, Pb and Zn exceeded the intervention threshold in Bozânta tailings site, while Pb content exceeded the intervention level within the area of the drinking water treatment plant. Cd showed a very high potential ecological risk in Bozânta area. The long-term exposure to HMs contributed to the selection of HM-tolerant and weakly adherent strains. Biofouling was significantly reduced under the influence of copper ions. Arthrobacter, Rhodococcus and Acidovorax strains with exceptional resistant profiles were isolated from the tailings site, indicating the important role of native microorganisms in rhizosphere ecosystems of contaminated sites.

中文翻译：

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长期接触重金属对 Baia Mare 地区（罗马尼亚马拉穆列什县）根际细菌的影响

摘要 本研究的目的是调查 Baia Mare 地区（罗马尼亚 Maramureş 县）的重金属 (HM) 污染程度及其对根际土壤微生物的影响。研究中包括了两个污染程度不同的地点：一个有着悠久的采矿活动历史，一个在饮用水安全区内。根际土壤样品在物理化学参数和 Cd、Cu、Pb 和 Zn 含量方面进行了表征。通过微量稀释法研究了天然细菌在毒性暴露下的 HM 耐受性和生物膜形成。鉴定了最具抗性的菌株，并确定了对 HMs 的最低抑制浓度。在 Bozânta 尾矿场，Cd、Cu、Pb 和 Zn 超过了干预阈值，而在饮用水处理厂区域内，铅含量超过了干预水平。镉在 Bozânta 地区显示出非常高的潜在生态风险。长期接触 HMs 有助于选择耐 HMs 和弱粘附菌株。在铜离子的影响下，生物污垢显着减少。从尾矿场中分离出具有特殊抗性特征的节杆菌、红球菌和酸食菌菌株，表明本地微生物在污染场地的根际生态系统中发挥着重要作用。