Deciphering the potential of Bacillus cereus HS-9 in cadmium bioremediation and ensuring rice safety

Cadmium (Cd) contamination in agricultural soils poses significant environmental and health risks due to its non-degradable and bio-magnifying nature. With the global imperative for eco-friendly Cd remediation strategies, microbial bioremediation emerges as a promising approach. Here, Bacillus cereus HS-9 was isolated from Cd-contaminated paddy soil using LB medium supplemented with 5 mg/L of Cd. HS-9 exhibited an impressive Cd removal efficiency of 95.44 % at a concentration of 5 mg/L. A rice pot experiment was conducted using Cd-contaminated soil, with HS-9 inoculation as the treatment group and non-inoculated soil as the control. The treatment group resulted in a 38.99 % reduction in soil Cd availability and a 34.33 % decrease in rice Cd content without affecting rice yield. The microbial community of the rice rhizosphere was analyzed using metagenome sequencing. The results revealed an increased abundance of czcA, frnE, and irlS genes in the soil microbiome, indicating enhanced Cd resistance and efflux capabilities. Microbial community showed significant shifts towards a beneficial microbial consortium, particularly marked by increases in Lysobacter and Sphingomonas genera which are known for their roles in heavy metal resistance and bioremediation. B. cereus HS-9 demonstrated significant potential for the bioremediation of Cd-contaminated soil. This study provides foundation for the development of microbial-based strategies for the eco-friendly remediation of heavy metal-polluted agricultural lands.