Encapsulation of microbial β-CA in ZIF-8-GA via MOF-assisted cell surface display system for low-temperature capture of CO₂

To address the limited CO₂ capture efficiency at low temperatures, a new engineering bioremediation strategy was proposed. This method combined surface display technology with ZIF-8-GA packaging to promote the production of cold-active carbonic anhydrase PsCA. The successful expression of BL21/pET-INPN-PsCA was confirmed through subcellular fractionation and protease accessibility assays. The ZIF-8-GA coating improved membrane integrity and conferred strong resistance to environmental stresses. The coated cells retained 57.7 % of their activity after 60 min of UV exposure and 52.2 % after 8 days of storage at 15 °C, demonstrating excellent environmental resilience. Coated cells maintained 60.4 % catalytic activity after 12 cycles of repeated use, highlighting their reusability compared to free cells at 38.5 %. At 15 °C, the consumption rate of Ca²⁺ was 78.6 % after 12 h and 91.5 % after 48 h. The efficient hydration of CO₂ by the biocatalyst at low temperatures was demonstrated by mineralization kinetics. Although enzymatic activity declined slightly to 64.2 % after 8 days of storage at 37 °C, it remained stable during subsequent reuse. Both coated and uncoated systems displayed good performance under varied environmental conditions, with the ZIF-8-GA exoskeleton offering prolonged enzymatic protection and structural stability. Collectively, the ZIF-8-GA assisted encapsulation of cell surface display system made a significant contribution to the continuous low-temperature storage of CO₂, constituting an effective improvement strategy for CO₂ capture and cold remediation.