A study on cadmium immobilization by bacterial consortia: <i>Achromobacter insuavis</i> SL8 and <i>Enterobacter cancerogenus</i> SL12

ABSTRACT Microbial bioremediation represents one of the most environmentally sustainable strategies for mitigating cadmium (Cd) pollution. This study employed an integrated approach combining spectroscopy, metabolomics, and proteomics to elucidate the molecular mechanisms underlying Cd detoxification in Achromobacter insuavis SL8 and Enterobacter cancerogenus SL12. The results demonstrated that both strains exhibit high Cd tolerance, with minimum inhibitory concentrations (MICs) of 600 mg/L and 400 mg/L for SL8 and SL12, respectively. In a 100 mg/L Cd solution, the strains achieved removal rates of 69.5% (SL8) and 70.8% (SL12), which increased to 80.9% under co-culture conditions. Spectroscopic analyses revealed that the co-culture facilitated Cd detoxification through the formation of CdS precipitates and modifications of key surface functional groups (phosphate, N-H, and C=O groups). Metabolomic and proteomic profiling indicated significant up-regulation of metabolites and proteins involved in metal transport, biosorption, chelation, energy metabolism, and antioxidant defense, collectively maintaining cellular Cd homeostasis. To validate field applicability, pot experiments showed Cd removal rates of 13% in soil and 20% in Chinese cabbage. This multi-omics investigation not only deepens the understanding of microbial adaptive responses to Cd stress, but also provides insights for developing novel microbial consortia for efficient and eco-friendly bioremediation of Cd-contaminated environments. IMPORTANCE Cadmium contamination in agricultural soils poses serious risks to food safety and human health. Despite being a highly sustainable approach for mitigating cadmium pollution, microbial bioremediation still lacks practical and effective solutions. In this study, we reveal how a two-member bacterial consortium ( Achromobacter insuavis SL8 and Enterobacter cancerogenus SL12) works together to immobilize Cd through complementary mechanisms. Through a multi-omics and spectroscopic approach, we discovered that the consortium not only outperforms individual strains in cadmium removal but also enhances plant growth while decreasing cadmium uptake in crops. These findings provide a scientific basis for developing effective bioremediation strategies using microbial partnerships. Our work advances the understanding of how bacteria cooperatively respond to heavy metal stress and offers a promising, eco-friendly approach to remediate cadmium-polluted soils, ultimately contributing to safer food production and improved environmental health.