High-efficient immobilization of uranium by biochar loaded mixed microorganisms composed of Bacillus and Pseudomonas

Microbial remediation has prominent advantages in the prevention and control of uranium-contaminated soil. However, its efficiency in uranium immobilization remains suboptimal. Here, a biochar loaded mixed microorganisms was innovatively constructed, composed of Bacillus subtilis, Bacillus cereus, Pseudomonas putida, and Pseudomonas aeruginosa (3:2:2:3 ratio). Results demonstrate that the biochar-microbial composite achieve an 80.17% reduction in diethylenetriaminepentaacetic acid-extractable uranium (DTPA-U), surpassing single-strain treatments and physical mixtures. Synergistic mechanisms involving adsorption, bioreduction, and biomineralization were elucidated via X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR). Dominant contributions from hydroxyl, carboxyl, amino and phosphate functional groups were also revealed. 16S rRNA high-throughput sequencing indicates the success colonization of the introduced microbes and their influence on the soil microbial community. This study pioneers a multifunctional biochar-microbe platform for synergistic uranium immobilization, offering actionable insights in situ bioremediation strategies.