Engineering light-driven biomineralization for a sustainable carbonate economy

Photosynthetic activity of cyanobacteria is a prominent driver of cell-surface catalysed extracellular calcium carbonate (CaCO 3 ) precipitation. This natural process termed “biomineralization” occurs only under specific circumstances but has given rise to significant carbonate rock formation throughout geological time. Engineering cyanobacterial cell surfaces for enhanced and constitutive biomineralization of abundant ocean-water dissolved Ca 2+ and flue-gas CO 2 into CaCO 3 may allow for the biotechnological re-capture of CO 2 released by industrial processes such as thermal decarboxylation of CaCO 3 . This may both limit net greenhouse gas emissions and transform CaCO 3 into a sustainable resource. Drawing from geological precedent and basic biological research, this perspective outlines promising synthetic biology strategies to convert cyanobacterial biomineralization into a cornerstone technology for a sustainable carbonate economy.