Direct Air Capture of CO₂ by Microalgae with Buoyant Beads Encapsulating Carbonic Anhydrase

Microalgae cultures have promise as a CO2 sink for atmospheric carbon and sustainable source of food chemical feedstocks. However, large-scale microalgae cultivation is currently limited by the need to provide dioxide from point sources, diffusion too slow. Carbonic anhydrase (CA) an effective enzyme facilitate dissolution that could be used enhance photosynthetic uptake this greenhouse gas. Here we investigate means retaining CA at surface algae ponds direct air capture cross-linking with glutaraldehyde (GA) before encapsulation into buoyant calcium alginate beads. Coomassie Blue dyeing Wilbur–Anderson assays confirmed successful bonding Microscopic images showed paraffin-embedded framework. The CA–GA beads retain virtually all hydrase activity throughout 10 assay cycles. Compared natural growth rate 22.7 ± 0.5 mg L–1 day–1, free increased productivity Nannochloropsis salina 37 3 day–1 40 1 respectively. further provided stable enhancement three rounds cultivation, confirming these can readily recovered re-used, which promising industrial biomass production.