SOIL Raw sequence reads

Phytoremediation is a potentially cost-effective way to remediate highly contaminated mine tailing sites. However, nutrient limitations, especially the deficiency of N, can hinder the growth of plants and impair the phytoremediation of mine tailings. Nevertheless, pioneer plants can successfully colonize mine tailings and exhibit potential for tailing phytoremediation. Diazotrophs, especially diazotrophic endophytes can promote the growth of their host plants. This was tested in a mine-tailing habitat by a combination of field sampling, DNA-stable isotope probing (SIP) analysis, and pot experiments in this study. Bacteria belonging to the genera Herbaspirillum, Rhizobium, Devosia, Pseudomonas, Microbacterium, and Delftia were crucial endophytes for Chinese silvergrass (Miscanthus sinensis) grown in the tailing, the model pioneer plant selected in this study. Further, DNA-SIP using 15N2 identified Pseudomonas, Rhizobium, and Exiguobacterium as putative diazotrophic endophytes of Miscanthus sinensis. Metagenomic-binning suggested that these bacteria contained essential genes for nitrogen fixation and plant growth promotion. Finally, bacteria associated with Rhizobium and Pseudomonas, two diazotrophic endophytes identified by DNA-SIP, were isolated from M. sinensis and were inoculated into Bidens pilosa L., another pioneer plant in mine tailings. The amendment of diazotrophic endophytes significantly increased the activity of nitrogen fixation and subsequently the growth of B. pilosa L. and the amended bacteria successfully colonized the plants. This study indicated that diazotrophic endophytes have the potential to promote the growth of various pinooner plants in mine tailings.