The multitasking microbe that turns CO? into minerals

In the future, could the walls of our houses be partly made from CO?? Researchers from EPFL's Soils Mechanics Laboratory, the University of Applied Sciences and Arts of Southern Switzerland (SUPSI) and the EPFL start-up Medusoil SA have demonstrated that Bacillus megaterium – a resilient and versatile microorganism commonly found in soil, freshwater and marine environments or even plant surfaces – can mineralize carbon dioxide (CO?) into calcium carbonate (CaCO?), the mineral that forms limestone and marble.

What sets this study apart is not just the biological feat itself, but the quality and origin of the mineral formed. Under high-CO? conditions – specifically, at concentrations over 470 times those found in the atmosphere – B. megaterium shifted its metabolic strategy.

Using an enzyme called carbonic anhydrase, it converted CO? into bicarbonate, which then reacted with calcium ions to form solid calcite. Astonishingly, 94% of the resulting mineral was derived directly from CO?, not from nitrogen-based compounds like urea.

"We know that dozens of bacteria have the potential to mineralize crystals," says Dimitrios Terzis, corresponding author, Research and Teaching associate at EPFL's Soil Mechanics Laboratory and co-founder of Medusoil SA. "However, what is unique about our work is that we showcase this can be done by directly using CO?. The potential that lies ahead is huge, and our teams can't wait to upscale and maximize it."

Image source: Cappa et al. (2025), Scientific Reports.