Potential biomarkers for different rare earth elements enrichment in soils around a rare earth tailings pond

Microorganisms in soil are very sensitive to changes in the environment. However, the effects that different levels of REEs contamination in soils have on microorganisms and the interactions between them are still unclear, and there was a lack of research on biomarkers for different rare earth enrichment. In this study, the concentration of REEs was divided into different accumulation levels, then the effects of REEs concentration on the diversity, structure and function were investigated by using Illumina high-throughput sequencing technology. Results showed that the accumulation of REEs reduced the diversity of soil bacterial communities, but did not affect the richness of bacterial communities. Proteobacteria, Actinobacteria and Chloroflexi were the most abundant bacteria around the rare earth tailings pond. Linear discriminant analysis Effect Size (LEfSe) showed that Halomonas, Aliifodinibius and Truepera could be potential biomarkers for soil samples with high concentrations of REEs. Sphingomonas was the biomarker in MC samples, while norank_Subgroup6, norank_Actinobacteria and RB41 were enriched in LC samples. Suggesting that these species could be used for reference in rare earth mine restoration. Function prediction by Tax4fun revealed the metabolic capacity of bacterial communities was inhibited under stress of REEs, and some of their functions were associated with human diseases. Redundancy analysis and Mantel test suggested that soil moisture content and rare earth element content were the most critical influencing factors in rare earth mining areas. The results show that the accumulation of rare earth elements has a significant impact on the diversity, composition and function of bacterial communities in rare earth mining areas. The indicator microorganisms in the soil with different enrichment levels of rare earths were found. It further reveals the structure and function of soil microbial communities around rare earth mines. At the same time, the potential risks to human health caused by soil pathog