An integrated sensing, adsorption, and recovery platform using engineered Escherichia coli for mercury remediation

Mercury (Hg), a persistent, bioaccumulative, and highly toxic global pollutant, poses a severe threat to aquatic ecosystems and human health. In this study, we constructed a multifunctional remediation platform based on engineered Escherichia coli that integrates real-time Hg²⁺ monitoring, efficient adsorption, and magnetic recovery. First, a tandem mercury-binding peptide (CAACAACAAC) was anchored on the bacterial surface via cell surface display technology, which significantly enhanced the Hg²⁺ adsorption capacity to nearly twice that of the control strain. Second, a highly sensitive mercury biosensor was developed using a T7 RNA polymerase-based signal amplification cascade; the introduction of degradation tags enabled post-translational regulation of the fluorescent protein, T7 RNA polymerase, and MerR, allowing real-time tracking of dynamic changes in mercury concentration. Co-expression of the adsorption and detection modules enabled the strain to perform simultaneous mercury adsorption and monitoring. Furthermore, amine-modified magnetic nanoparticles were crosslinked with the engineered bacteria to construct a magnetic complex (HG-GFP@MNP), achieving approximately 90% mercury removal and over 90% cell recovery in natural water bodies. Finally, ecological safety was assessed using the Pseudorasbora parva. After two rounds of treatment, mercury accumulation in various fish tissues was significantly reduced, and hepatic oxidative stress markers-including superoxide dismutase, catalase, glutathione reductase, glutathione S-transferase activities, and malondialdehyde content-returned to normal levels. This study provides a transferable technical strategy for the bioremediation of heavy metal pollution.