Phototrophic Nitrogen Fixation, a Neglected Biogeochemical Process in Mine Tailings?

Abstract

Biological nitrogen fixation (BNF) has important ecological significance in mine tailing by contributing to the initial accumulation of nitrogen. In addition to chemolithotrophic and heterotrophic BNF, light may also fuel BNF in oligotrophic mine tailings. However, knowledge regarding the occurrence and ecological significance of this biogeochemical process in mine tailings remains ambiguous. The current study observed phototrophic BNF in enrichment cultures established from three primary successional stages (i.e., original tailings, biological crusts, and pioneer plants) of tailings. Notably, phototrophic BNF in tailings may be more active at vegetation stages (i.e., biological crusts and pioneering plants) than in bare tailings. DNA-stable isotope probing identified Roseomonas species as potential aerobic anoxygenic phototrophs responsible for phototrophic BNF. Furthermore, metagenomic binning as well as genome mining revealed that Roseomonas spp. contained essential genes involved in nitrogen fixation, anoxygenic photosynthesis, and carbon fixation, suggesting their genetic potential to mediate phototrophic BNF. A causal inference framework equipped with the structural causal model suggested that the enrichment of putative phototrophic diazotrophic Roseomonas may contribute to an elevated total nitrogen content during primary succession in these mine tailings. Collectively, our findings suggest that phototrophic diazotrophs may play important roles in nutrient accumulation and hold the potential to facilitate ecological succession in tailings.

Fast Bacterial Succession Associated with the Decomposition of Larix gmelinii Litter in Wudalianchi Volcano

“…There was no significant difference in the C content of litter at different decomposition stages of Larix gmelinii, but chemoheterotrophy and aerobic chemoheterotrophy significantly increased with the progress of decomposition, which indicates that many bacteria cannot fix carbon, some show that some bacteria groups obtain carbon and energy by oxidizing organic matter for their growth promoting the assimilation and utilization of leaf litter carbonby bacteria [47,49]. The functional groups involved in the nitrogen cycling process are urea degradation, with Mesorhizobium, Masilia and Roseomonas are dominant, which is the same results in Mount Huangshan [50,51].…”

Microbially mediated sulfur oxidation coupled with arsenate reduction within oligotrophic mining–impacted habitats

“…After incubation, genomic DNA was extracted from samples by using the DNeasy Powersoil Kit (Qiagen, Dresden, Germany) following the manufacturer’s protocol. Total DNA from each sample was then separated into isopycnic fractions by ultracentrifugation according to a published protocol [ 25 , 26 ]. Details of the SIP sample processing are provided in Supplementary Method 3 .…”

Differential Mechanisms of Microbial As(III) and Sb(III) Oxidation and Their Contribution to Tailings Reclamation

“…Primary succession is a critical process that leads to tailing reclamation. The indigenous microbial communities contribute to primary succession of tailing sites via nutrient accumulation and facilitation of plant establishment. − Nutrient limitation, especially bioavailable nitrogen and phosphate, is a major factor that limits the reclamation of tailings. − Given their prevalence in mine tailings, ,, the As­(III) and Sb­(III) oxidizers could be critical for providing these essential services during tailing reclamation. In fact, As­(III) and Sb­(III) oxidation have both been suggested as important energy sources for nitrogen fixation identified in previous studies. ,,− Although the functional population, including Serratia , Rhodocyclaceae , and Rhizobiaceae , that mediated these processes have been proposed, , the relative preference of As­(III) and Sb­(III) oxidation to fuel nitrogen fixation have not been investigated.…”