Response of bacterial and fungal composition in tailings to Mn pollution

Microorganisms are crucial for natural remediation of heavy metal pollution in mining areas. The regional survey and process analysis of Mn mine microbes is still limited. We investigated microbial species composition in tailings and adjacent soils of seven typical Mn mining areas in wet mid-subtropical China. The Mn bioavailable content in tailings was 55 times higher than in soils. Compared to soils, the heavy metal pollution in tailings reduced the hydrolase activities and microbial species diversity by 97 % and 38 %, respectively. The co-occurrence network of bacterial and fungal species in tailings was dominated by symbiosis and synergism, and their network complexity was lower than that in soils. Linear discriminant analysis of effect size revealed that Ralstonia, Acidisoma, and Talaromyces were the species most stimulated by Mn pollution because their relative and absolute abundance in tailings was much higher than those in soils (p < 0.001). These key species defined the co-occurrence networks and affected metabolic pathways of microbial communities. Electrical conductivity and its interaction with Mn bioavailability strongly affected tailings microbial key species. This work identified the key species adapted to extreme Mn pollution in tailings, which can be used for bioremediation and maintenance of ecosystem functions in Mn-contaminated soils.