Hyperaccumulator extracts promoting the phytoremediation of rare earth elements (REEs) by Phytolacca americana: Role of active microbial community in rhizosphere hotspots

Shengpeng Yan; Shengwen Xu; Shihan Lei; Yuan Gao; Keyi Chen; Xiaoyu Shi; Yingying Guo; Nataliya Bilyera; Ming Yuan; Huaiying Yao

doi:10.1016/j.envres.2024.118939

Hyperaccumulator extracts promoting the phytoremediation of rare earth elements (REEs) by Phytolacca americana: Role of active microbial community in rhizosphere hotspots

Environ Res. 2024 Apr 15;252(Pt 3):118939. doi: 10.1016/j.envres.2024.118939. Online ahead of print.

Authors

Affiliations

¹ Key Laboratory of Green Chemical Engineering Process of Ministry of Education, School of Environmental Ecology and Biological Engineering, Wuhan Institute of Technology, Wuhan, 430205, China.
² Geo-Biosphere Interactions, Department of Geosciences, University of Tuebingen, 72076, Tuebingen, Germany.
³ Key Laboratory of Green Chemical Engineering Process of Ministry of Education, School of Environmental Ecology and Biological Engineering, Wuhan Institute of Technology, Wuhan, 430205, China. Electronic address: yuan_ming_6@foxmail.com.
⁴ Key Laboratory of Green Chemical Engineering Process of Ministry of Education, School of Environmental Ecology and Biological Engineering, Wuhan Institute of Technology, Wuhan, 430205, China; Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; Zhejiang Key Laboratory of Urban Environmental Processes and Pollution Control, Ningbo Urban Environment Observation and Research Station, Chinese Academy of Sciences, Ningbo, China.

PMID: 38621629
DOI: 10.1016/j.envres.2024.118939

Abstract

The increased usage of rare earth elements (REEs) leads to the extensive exploitation of rare earth mines, and the REEs pollution in soil caused by the legacy mine tailings has brought great harm to environment and human health. Although Phytolacca americana can remove REEs from contaminated soil to some extent, there is still an urgent problem to improve its efficiency. Hyperaccumulator extract is a new organic material with potential in metal phytoextraction, but its role in REEs phytoremediation and the related underlying processes remain unclear. In this study, hyperaccumulator extracts from P. americana root (PR), stem (PS), leaf (PL) and EDTA were used to improve the phytoremediation efficiency of REEs with P. americana. Soil zymography was applied to assess the enzyme hotspots' spatial distribution in the rhizosphere, and the hotspots' microbial communities were also identified. The results indicated that the application of hyperaccumulator extracts improved the biomass and REEs uptake of P. americana, and the highest REEs content in plant was observed in the treatment of PS, which increased 299% compared to that of the control. Hotspots area of β-glucosidase, leucine aminopeptidase and acid phosphatase were concentrated in the pant rhizosphere along the roots and increased 2.2, 5.3 and 2.2 times after PS application compared to unamended soils. The PS application increased the relative abundance of Proteobacteria, Cyanobacteria, Bacteroidota and Firmicutes phyla in rhizosphere. Soil fungi have a higher contribution on promoting REEs activation than that of bacteria. Available P and extractable REEs were leading predictors for the plant biomass and REEs concentrations. The co-occurrence network showed that the application of PS creates a more efficient and stable microbial network compared to other treatments. In conclusion, stem-derived hyperaccumulator extract is excellent in stimulating REEs phytoremediation with P. americana by improving hotspots microbial activities and form a healthy rhizosphere microenvironment.

Keywords: Hyperaccumulator extract; Microbial community structure; Phytolacca americana; Rare earth elements (REEs); Soil zymography.