Environmental Parameters Determine the Structure of Soil Bacteria under Different Land use Types in Tailings Area

Soil microorganisms contribute substantially to a wide range of services and thereby improve recovery in ecosystem restoration. However, there is relatively limited information on how microbial communities respond to different land-use types with similar plant species and their potential roles in supporting soil restoration in mine tailings. To understand the importance of the response of soil microbial communities to the stress of tailings area in different soil habitats, this article selected three different land use types (Tailings area, Buffer zone and Vegetable field) as the variables in the Yanzibian tailings area in Ningqiang, Shaanxi Province, China. Soil physicochemical properties and heavy metal concentrations of the different land use types were compared. Illumina MiSeq. 2500 Sequencing Technology was used to analyze the abundance and structural diversity of the microbial community in soil samples. The results showed that most of the soil samples were unsafe with multiple metals. All soil samples in the buffer zone and tailings ponds were acidic. With the acidity decreased, bacterial community richness and diversity increased significantly. Briefly, different environmental factors and soil microbial communities were significantly distinct across different land-use types. Cu, Zn, Pb, pH, MC (Moisture content), TN (Total nitrogen), TP (Total phosphorus), and TK (Total potassium) were essential factors affecting the abundance and structural diversity of soil microbial communities across three different land-use types. As a result, Actinobacteria, Alphaproteobacteria, and Gammaproteobacteria were the top dominant classes in the buffer zone and Vegetable field soils, while Sulfobacillia dominated in tailings pond soils. Further, we found that with the continuous decline of the pH, the dominant genera transferred from norank_f__norank_o__Vicinamibacterales, Bacillus and Nocardioides to the norank_f__norank_o__Gaiellales and norank_f__norank_o__Acidobacteriales, then to Sulfobacillus. These confirmed that the responses of microbiota to heavy metals stress varied in different land-use types. Together, this study provides important information on the occurrence and distribution of soil microbiomes in tailings areas and their potentially beneficial roles in soil restoration.