Chemolithoautotrophic Antimonite Oxidation Coupled Nitrogen Fixation in the Rhizosphere of Local Plant in Antimony Tailing Area

This is the authors' abstract. We don't add key points for this paper.

Antimony (Sb) tailings pose a significant environmental challenge. N-fixing microorganisms are essential for nutrient accumulation and plant colonization in degraded habitats. However, the oligotrophic conditions of tailings often inhibit the energy-intensive N-fixing process. This study identified a chemolithoautotrophic Sb(III) oxidation-coupled nitrogen fixation (SbNF) pathway in the rhizosphere of local plants. SbNF integrates biological detoxification and nutrient accumulation, enabling plant colonization and ecological restoration of degraded habitats. Multi- omic analyses reveal that Sb content strongly shapes the composition of Sb-oxidizing and N-fixing bacterial communities in the rhizosphere. Abundant marker genes for carbon fixation ( cbbL ), Sb(III) oxidase ( aioAB/anoA ), and nitrogenase ( nifH ) were consistently detected in SbNF metagenome-assembled genomes. Positive correlations between gene abundances associated with autotrophic potential ( aioA - cbbL ) and coupling potential ( aioA - nifH ) were observed in the rhizoplane but not in the endosphere. In addition to genetic potentials, high-throughput cultivation of native SbNF-isolates (e.g., Pseudomonas, Arthrobacter, and Sphingomonas ) confirmed their rapid Sb(III) oxidation coupling autotrophic growth and nitrogen fixation. Isolates also exhibited plant growth-promoting traits, including indole-3-acetic acid production, phosphate solubilization, and siderophore secretion, providing multiple benefits to host plants. Co-cultivation of these isolates revealed minimal antagonism, suggesting the potential for designing synthetic microbial communities for sustainable phytoremediation. Cross-validation further suggests that SbNF is widespread in the rhizosphere of various local plants. These findings uncover a novel biogeochemical process in the rhizosphere, linking mineral oxidation, autotrophic growth, and nitrogen fixation, highlighting its importance for the ecological restoration of degraded tailing area.