Genetically engineered whole-cell biocatalyst for efficient CO2 capture by cell surface display of carbonic anhydrase from Bacillus cereus GLRT202 on Escherichia coli

CO₂ sequestration is important for reducing greenhouse effects. Carbonic anhydrase (CA) from bacteria has a promising role because it can be modified by genetic techniques and bioengineering. In this study, the CA from B. cereus GLRT202 (Bc-CA) was genetically engineered and anchored on the surface of E. coli by using the N-domain of the ice nucleation protein from P. syringae (INPN). Both surface-displayed and cytosolic Bc-CA yielded high expression levels of CA when induced with 0.5 mM IPTG. It exhibited no adverse influence on the host cell growth. Additionally, surface-displayed Bc-CA enhanced its stability and specificity compared to cytosolic expressed Bc-CA. The CA activity of whole-cell surface-displayed cells was 1.66-fold higher (5.19 U/mL) than that of the cytosolic form. Besides the advantages of higher activity, the whole-cell displaying CA was comparatively stable, with better storage (at 4 ℃) and resting culture stability (at 37 ℃). The whole-cell biocatalyst induced the calcite precipitation, which indicated that the cell facilitated the CO₂ capture. XRD, FTIR, and FESEM characterized calcite precipitates thus obtained. This study demonstrates that Bc-CA can be correctly expressed on the E. coli surface through fusion with the INPN. This leads to an effective whole-cell biocatalyst with enhanced stability and specificity of the enzyme for efficient CO₂ capture applications.