Biomimetic CO₂ Capture Unlocked through Enzyme Mining: Discovery of a Highly Thermo- and Alkali-Stable Carbonic Anhydrase

Taking immediate action to combat the urgent threat of CO₂-driven global warming is crucial for ensuring a habitable planet. Decarbonizing the industrial sector requires implementing sustainable carbon-capture technologies, such as biomimetic hot potassium carbonate capture (BioHPC). BioHPC is superior to traditional amine-based strategies due to its eco-friendly nature. This innovative technology relies on robust carbonic anhydrases (CAs), enzymes that accelerate CO₂ hydration and endure harsh industrial conditions like high temperature and alkalinity. Thus, the discovery of highly stable CAs is crucial for the BioHPC technology advancement. Through high-throughput bioinformatics analysis, we identified a highly thermo- and alkali-stable CA, termed CA-KR1, originating from a metagenomic sample collected at a hot spring in Kirishima, Japan. CA-KR1 demonstrates remarkable stability at high temperatures and pH, with a half-life of 24 h at 80 °C and retains activity and solubility even after 30 d in a 20% (w/v) K₂CO₃/pH 11.5 solution─a standard medium for HPC. In pressurized batch reactions, CA-KR1 enhanced CO₂ absorption by >90% at 90 °C, 20% K₂CO₃, and 7 bar. To our knowledge, CA-KR1 constitutes the most resilient CA biocatalyst for efficient CO₂ capture under HPC-relevant conditions, reported to date. CA-KR1 integration into industrial settings holds great promise in promoting efficient BioHPC, a potentially game-changing development for enhancing carbon-capture capacity toward industrial decarbonization.