Abstract

Background and aims

Mercury (Hg) contamination poses severe human and environmental health risks. We aimed to evaluate the colonization of Hg-contaminated sites by native plants and the prokaryotic composition of rhizosphere soil communities of the dominant plant species.

Methods

A field study was conducted at a Hg-contaminated site in Romania. Metal concentrations in soil and plant samples were analyzed using portable X-ray fluorescence spectrometry. The prokaryotic composition of rhizosphere soil communities was determined through 16S rRNA amplicon sequencing and community functionality was predicted through PICRUSt2.

Results

Site-specific trace metal distribution across the site drove plant species distribution in the highly contaminated soil, with Lotus tenuis and Diplotaxis muralis associated with higher Hg concentrations. In addition, for the bacterial communities in the rhizosphere soil of D. muralis, there was no observable decrease in alpha diversity with increasing soil Hg levels. Notably, Actinomycetota had an average of 24% relative abundance in the rhizosphere communities that also tested positive for the presence of merA, whereas in the absence of merA the phylum’s relative abundance was approximately 2%. merA positive rhizosphere communities also displayed an inferred increase in ABC transporters.

Conclusions

The results suggest a dependence of species-wise plant survival on local trace metal levels in soil, as well as an intricate interplay of the latter with rhizosphere bacterial diversity. Knowledge of these interdependencies could have implications for phytoremediation stakeholders, as it may allow for the selection of plant species and appropriate soil microbial inoculates with elevated Hg tolerance.

中文翻译：

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汞污染场地的植物定植者：微量金属和相关的根际细菌

摘要

背景和目标

汞 (Hg) 污染对人类和环境健康造成严重风险。我们的目的是评估本地植物在汞污染地点的定殖以及优势植物种根际土壤群落的原核组成。

方法

在罗马尼亚的汞污染地点进行了实地研究。使用便携式 X 射线荧光光谱仪分析土壤和植物样品中的金属浓度。通过 16S rRNA 扩增子测序确定根际土壤群落的原核组成，并通过 PICRUSt2 预测群落功能。

结果

整个场地内特定地点的微量金属分布驱动了高度污染土壤中的植物物种分布，其中Lotus tenuis和Diplotaxis muralis与较高的汞浓度相关。此外，对于D. muralis根际土壤中的细菌群落来说，随着土壤汞含量的增加，α多样性没有明显下降。值得注意的是，放线菌门在根际群落中平均相对丰度为 24%，并且merA的存在也呈阳性，而在不存在merA的情况下，该门的相对丰度约为 2%。merA阳性根际群落也显示出 ABC 转运蛋白的推断增加。

结论

结果表明，物种间植物的生存依赖于土壤中局部微量金属水平，以及后者与根际细菌多样性之间复杂的相互作用。了解这些相互依赖性可能会对植物修复利益相关者产生影响，因为它可能允许选择具有较高汞耐受性的植物物种和适当的土壤微生物接种。