Novel Engineered Living Materials for Integrated Detection, Remediation, and Recovery of Cadmium Pollution

ABSTRACT

Heavy‐metal emissions pose severe environmental hazards, with Cd ²⁺ contamination being particularly critical. However, current strategies for Cd ²⁺ detection and remediation remain limited and often inflict secondary ecological damage. Here, we engineered Bacillus subtilis as a chassis to construct a Cd ²⁺ ‐responsive biosensor (CJSora) by integrating the endogenous promoter of cadA (pcadA) with a T7RNAP ‐based signal amplification module. The resulting sensor enables monitoring of environmental Cd ²⁺ with high specificity and sensitivity across a 0–100 µM range. To achieve intelligent detection and remediation, we further developed an engineered living material (CJSsorX) capable of autonomous response to Cd ²⁺ pollution. Under low Cd ²⁺ conditions (e.g., agricultural soils), surface‐displayed Cd ²⁺ ‐binding protein CadR efficiently captures and recovers Cd ²⁺ from the environment. When Cd ²⁺ levels exceed the adsorption capacity, intracellular overexpression of the aerobic sulfate reduction pathway ( CysE and PatB ) catalyzes the biomineralization of Cd ²⁺ into CdS nanoparticles, enabling spatially modular remediation with enhanced efficiency and sustainability. After remediation, Cd ²⁺ can be reclaimed using a functional peptide (TVNFKLY) with specific affinity for Fe ₃ O ₄ magnetic nanoparticles. As a proof of concept, CJSsorX was applied to the removal of Cd ²⁺ from contaminated soils and wastewater. The engineered material achieved 83.64% removal in soils and up to 99.56% removal in water. Overall, this work establishes a B. subtilis –based intelligent living material with integrated sensing, remediation, and recovery capabilities, offering a promising and sustainable strategy for combating Cd ²⁺ pollution.