Metal-tolerant microbial succession mediated by mining reclamation improves network stress resistance

The development of heavy metal-resistant microbial species (STS) and their interactions in the reclaimed soil play a vital role in improving the stability of mining area ecosystems. However, the development of the STS in reclaimed soil (Re) and the interactions to resist heavy metal stress (HMs) for maintaining the stability of co‑occurrence networks is still unclear. Therefore, this study employed high-throughput sequencing and differential abundance testing to explore the mechanisms of STS changes and the formation of co‑occurrence network resistance to HMs in reclaimed soil succession. Our results revealed that (1) Re treatment significantly improved the physicochemical properties of the soil and reduced the levels of HMs. Compared with the control group (CK), the heavy metal content in Re treatment decreased as follows: Hg (50.76%) > Cd (46.43%) > Cu (43.91%) > As (35.89%) > Pb (33.49%) > Cr (24.39%); (2) Compared with CK, the Shannon, ACE, and Observed species indices of bacteria in Re increased significantly by 11.70%, 549.33%, and 392.00% (p < 0.05), respectively. Additionally, Re significantly altered the β-diversity of bacterial communities (p < 0.01); (3) Proteobacteria, Acidobacteria, Bacteroidetes, and Chloroflexi were identified as the STS mediated by mining reclamation, and their changes exhibited a significant positive correlation with pH, SOM, and heavy metal content; (4) Compared with CK, the changes in STS increased the number of network modules in Re. The enrichment of Chloroflexi in the first four network modules in Re showed positive effects on Cu, Cd, and Pb stress, and taxa communities in module 3 may have a certain role in resisting As and Cr stress. Our results indicate the mechanisms of STS development and co‑occurrence network resistance in the long-term reclamation process of mining areas, thereby providing valuable insights for a deeper understanding of the role of microbes in ecological restoration of mining areas.