Abstract:

Phosphate-solubilizing bacteria-mediated biomineralization has great potential for heavy metal remediation， yet its application efficiency and underlying mechanisms in fragile alpine ecosystems remain poorly understood. A cold-tolerant phosphate-solubilizing strain Serratia quinivorans SH was isolated from an alpine tailings reservoir， and its phosphorus-solubilizing capacity， cadmium （Cd） tolerance and Cd immobilization mechanism under low-temperature conditions were systematically explored. The results showed that the maximum net soluble phosphorus concentration of strain SH reached 210.6 mg·L^-1 under low temperature， and the strain exhibited prominent tolerance to Cd stress at 5~40 mg·L^-1. Furthermore， the net soluble phosphorus concentration ranged from 187.2 to 210.6 mg at 5~15 ℃， with the optimal pH of 7~8 and optimal C/N ratio of 20∶1. Adsorption-precipitation experiments revealed that the maximum net Cd adsorption rate and net precipitation rate of strain SH were 83.3% and 35%， respectively. Characterizations via scanning electron microscopy-energy dispersive X-ray spectroscopy （SEM-EDS） verified that strain SH transformed Cd into stable phosphate precipitates. Whole-genome sequencing analysis further identified functional genes involved in phosphorus solubilization and heavy metal resistance. The results showed that the cold-resistant phosphate-solubilizing strain Serratia quinivorans SH possesses low-temperature phosphorus-solubilizing ability and Cd biomineralization capacity， which can provide strain resources and theoretical support for the remediation of heavy metal pollution in alpine tailings.

Key words: phosphate-solubilizing bacteria, alpine tailings, cadmium contamination, biomineralization