Microbial community structure and nitrogen cycling in an area affected by the tailings dam collapse under a rehabilitation process

The rehabilitation of areas affected by iron ore tailings has significantly altered soil properties and microbial communities ( p < 0.05). This study examines the recovery of bacterial communities and nitrogen cycling in two rehabilitated areas impacted by the B1 dam rupture: DA1, a stream channel area with significant engineering intervention, and DA2, near a forest with minimal intervention. Using microbial 16S rRNA gene sequencing we found that Pseudomonadota, Actinobacteriota, Acidobacteriota, Chloroflexota, and Gemmatimonadota represent about 71 % of the total bacteria abundance in rehabilitated areas, we also identified 7 bacterial genera ( Terrabacter , Neo b11, Qipengyuania , Curtobacterium , Terriglobus , Parasegetibacter and Rhodopseudomonas ) as biomarkers for DA1, 3 ( Clostridium , Ensifer and Lacibacter ) for DA2, and 8 ( Fodinicola , Roseiarcus , Acidipila , Candidatus Udaeobacter , Planotetraspora , Mycobacterium and Clade Ia) for a reference (REF) area. Genera in DA2 and REF were associated with nutrient cycling and plant growth, while DA1 displayed a wider range of metabolisms and degradation capacities. Microbial network analysis revealed more complex networks in rehabilitated areas DA1 (nodes = 3.186; edges = 6.480) DA2 (nodes = 3.224; edges = 6.521) than the reference (nodes = 2.175; edges = 3.020). Nitrogen cycle-related genera were present in both areas, with no significant difference ( p > 0.05) in the abundance of nifH , narG and amoA genes, suggesting that technosol supports efficient nitrogen cycling recovery. Overall, the study demonstrates microbial structure and function recovery in impacted areas, with technosol playing a beneficial role, even in regions with complex engineering needs. These findings highlight the potential of technosol for future environmental recovery efforts following dam collapses, motivating us to continue our research and innovation in this field. • Biomarkers can differentiate the rehabilitated areas of impacted areas. • The rehabilitated areas presented more connected networks than was observed in REF. • Engineering approach in affected area allowed the recovery of the soil microbiota and its ecological functions. • Technosols can accelerate the rehabilitation of areas affected by the dam breach.