Surface display of Ces17 in Escherichia coli for enhanced biodegradation of plasticizers

Phthalate acid esters (PAEs), extensively employed as plasticizers, have emerged as persistent environmental pollutants that pose serious threats to ecosystems and human health. Effective and sustainable strategies for their biodegradation are urgently needed. In this study, a whole-cell biocatalyst was developed by engineering Escherichia coli BL21(DE3) to surface-display the carboxylesterase Ces17 derived from Bacillus licheniformis DBP-4. The ces17 gene was fused to the N-terminal domain of the ice nucleation protein (INPN) from Pseudomonas syringae to facilitate membrane anchoring. Successful surface localization of Ces17 was verified by SDS-PAGE analysis and fluorescence microscopy. The displayed enzyme exhibited optimal catalytic activity at 40 °C and pH 9.0, and demonstrated enhanced storage stability, retaining approximately 71 % of its initial activity after 35 days at 4 °C, compared to only 34 % for its purified counterpart. Biodegradation assays revealed that 1 U of the surface-displayed Ces17 efficiently degraded 81.5 % of dimethyl phthalate, 62.0 % of diethyl phthalate, and 87.0 % of diisobutyl phthalate within 8 h, exhibiting superior performance in both efficiency and operational stability. These findings highlight the advantages of enzyme surface display for improving catalytic properties and durability, and propose a robust whole-cell biocatalytic system with significant potential for PAEs remediation in environmental applications.