Microbial approaches to cadmium stress in the soil–plant interface: current understanding and biotechnological solutions for sustainable remediation

Cadmium (Cd) contamination poses a critical threat to agriculture, food security, and human health due to its high solubility, toxicity, and bioavailability. Conventional remediation methods are often expensive, inefficient, and environmentally damaging, highlighting the urgent need for sustainable, biotechnology-based alternatives. This review explores microbial remediation as a promising strategy for Cd detoxification, focusing on the mechanisms that confer microbial Cd tolerance, including cell wall modification, biofilm formation, efflux systems, intracellular chelation, and genetic adaptation. Special emphasis is placed on plant growth-promoting rhizobacteria (PGPR) and endophytes, which mitigate Cd stress in plants by enhancing nutrient uptake, producing phytohormones, modulating antioxidant activity, and regulating metal transporter gene expression. The co-application of PGPR with soil amendments such as biochar and nanoparticles is shown to further improve Cd immobilization, plant resilience, and crop yield. Advancements in omics technologies and artificial intelligence (AI) offer deeper insights into microbial Cd resistance pathways, enabling the development of tailored bioinoculants and genetically engineered strains through tools like CRISPR. By integrating traditional microbiology with modern innovations, this review outlines next-generation solutions for effective Cd remediation, positioning Cd-tolerant microbes as key tools for sustainable agriculture and environmental protection.