Stabilization and mechanism of uranium sequestration by a mixed culture consortia of sulfate-reducing and phosphate-solubilizing bacteria

In this study, a highly efficient phosphate-solubilizing bacteria (PSB) (Pantoea sp. grinm-12) was screened out from uranium (U) tailings, and the carbon and nitrogen sources of mixed culture with sulfate-reducing bacteria (SRB) were optimized. Results showed that the functional expression of SRB-PSB could be promoted effectively when glucose + sodium lactate was used as carbon source and ammonium nitrate + ammonium sulfate as nitrogen source. The concentration of PO43- in the culture system could reach 107.27 mg center dot L-1, and the sulfate reduction rate was 81.72%. In the process of biological stabilization of U tailings by mixed SRB-PSB culture system, the chemical form of U in the remediation group was found to transfer to stable state with the extension of remediation time, which revealed the effectiveness of bioremediation on the harmless treatment of U tailings. XRD, FT-IR, SEM-EDS, highthroughput sequencing, and metagenomics were also used to assist in revealing the microstructure and composition changes during the biological stabilization process, and explore the microbial community/functional gene response. Finally, the stabilization mechanism of U was proposed. In conclusion, the stabilization of U in U tailings was realized through the synergistic effect of bio-reduction, bio-precipitation, and bio-adsorption.

Automated summary

A highly efficient phosphate-solubilizing bacteria (PSB) was isolated from uranium tailings, and the carbon and nitrogen sources for mixed culture with sulfate-reducing bacteria (SRB) were optimized. The study found that glucose + sodium lactate as carbon source and ammonium nitrate + ammonium sulfate as nitrogen source effectively promoted the functional expression of SRB-PSB. The concentration of PO43- in the culture system reached 107.27 mg center dot L-1, and the sulfate reduction rate was 81.72%. The study also revealed the effectiveness of bioremediation in the harmless treatment of U tailings.