SRA

Degraded soils generated by mining, known as tailings, are major environmental threats to the surrounding ecosystems. The reclamation of tailings is an urgent necessity globally. Tailing reclamation, however, is often impeded due to the adverse environmental conditions, with depleted key nutrients (i.e., nitrogen N and phosphorus P) and elevated sulfur and metal(loid)s concentrations. Establishment of biocrusts, especially moss-dominated biocrusts, significantly accelerate nutrient accumulation, and therefore is an essential stage for natural reclamation of tailings. Although suggested to play an important role in biocrust formation, the microbial community composition and key metabolisms in moss-dominated biocrusts remain largely unknown. The current study aimed to elucidate the key microbial metabolisms and identify the community members that mediate these processes. Microbial sulfur (S) and arsenic (As) oxidation were found to be important energy metabolisms adopted by biocrust community in tailings. The dominant bacterial families, such as Beijerinckiaceae, Burkholderiaceae, Hyphomicrobiaceae, and Rhizobiaceae, were inferred as putative S and As oxidizers. The presence of S and As improved biocrust formation and enhanced nutrient acquisition rates (nitrogen fixation and phosphorus solubilization). Microbial S and As oxidation, as well as N fixation and P solubilization) in biocrusts might be augmented by phages that encode auxiliary metabolism genes.