Biological Carbon Capture Using Spinach Carbonic Anhydrase Immobilized on Magnetite Nanoparticles

Abstract Bio-based carbon capture, utilization, and storage (CCUS) presents a promising alternative to conventional CCU methods, primarily due to its inherent potential for valorization. In the present study, carbonic anhydrase extracted from spinach leaves (Spinacia oleracea) was immobilized onto citric acid-functionalized magnetite nanoparticles (Fe3O4@CA NPs). This bio-nano hybrid functions as an efficient catalyst for enhancing CO2 solubility by accelerating its conversion to bicarbonate (HCO3 −), thereby overcoming the low aqueous solubility of gaseous CO2, a known limiting factor in photosynthetic autotrophs. Growth experiments using Escherichia coli cultures supplemented with these NPs demonstrated a ~62% increase in biomass production compared to the control group when the culture was sparged with atmospheric air, demonstrating that carbonic anhydrase-immobilized NPs effectively facilitated the uptake of atmospheric CO2 and redirected it into cellular biomass. Considering that 1 g E. coli dry cell weight can capture ~86 mg CO2, this approach can be used for carbon capture and production of fermentation-derived value-added products. Moreover, such systems hold significant potential for applications in algal biofuel production and the cultivation of slow-growing organisms, such as cyanobacteria, where efficient carbon assimilation is crucial for their growth.