Tailing_primariy succession Metagenome

Biological N2 fixation (BNF) has important environmental implications in tailings by contributing to the initial accumulation of N. However, knowledge regarding the phototrophic diazotrophs in mine tailings is still very limited. The current study observed the occurrence of phototrophic BNF in three successional stages of tailings (original tailings, biological crusts, and grasslands) across South China, suggesting that the potential for phototrophic BNF may be widespread in tailings. Members of Brevundimonas and Roseomonas were identified as putative microorganisms responsible for phototrophic BNF by DNA-stable isotope probing. Furthermore, metagenomic-binning demonstrated that Brevundimonas and Roseomonas contained essential genes involved in carbon fixation, nitrogen fixation, and photosynthesis, indicating their genetic potentials for phototrophic BNF. In addition, meta-analysis demonstrated that these phototrophic diazotrophs are widespread in different types of tailings among across South China. Furthermore, random forests and structural equation model demonstrated that the phototrophic diazotrophs could provide bioavailable carbon and nitrogen to tailings through carbon and nitrogen fixation. Our study may broaden the fundamental understanding of phototrophic BNF in the tailings, especially during primary succession.