Engineered bacteria speed up ocean carbon removal in Harvard study

Researchers at Harvard University's Wyss Institute have genetically engineered a marine bacterium to speed up rock weathering in seawater, removing more carbon dioxide from the atmosphere in the process. The findings, published Friday in Nature Biotechnology, demonstrate that the modified microbe accelerated the dissolution of the silicate mineral olivine by 2.6-fold in custom bioreactors fed with raw seawater from Boston Harbor.interestingengineering+2

How It Works

The team, led by Wyss Institute faculty members Pamela Silver and Michael Springer, modified Alteromonas macleodii, a common ocean bacterium, to continuously produce siderophores — molecules that strip iron oxide (rust) from mineral surfaces. In nature, iron released during olivine weathering oxidizes and coats the mineral, slowing further dissolution and limiting CO2 capture. Wild bacteria produce siderophores to harvest iron but shut off production once they have enough for growth.wyss.harvard+1

"Once wild bacteria have enough iron to grow, they stop making siderophores completely," said first author Neil Dalvie, who led the engineering work as a postdoctoral fellow in Silver's lab. "To enable enhanced weathering at scale, we engineered A. macleodii to always produce siderophores. We essentially decoupled siderophore production from environmental iron levels."wyss.harvard

From Lab to Pilot Scale

After promising small-scale results using eVOLVER bioreactors, the team built pilot-scale systems loaded with several kilograms of green olivine sand submerged in gallons of unprocessed seawater. Operating at steady state, the system captured 0.5 grams of atmospheric CO2 per day. A life-cycle analysis conducted in collaboration with Steven Davis's group at the Stanford Doerr School of Sustainability confirmed that the approach can achieve net carbon removal and identified the parameters needed for industrial viability.interestingengineering+1

Path Forward

The researchers envision growing the engineered bacteria in large open basins resembling sewage treatment facilities, continuously pumping seawater through and releasing alkaline, carbon-rich water back into the ocean. Further work will focus on identifying economically viable mineral feedstocks and exploring whether valuable metals can be extracted alongside carbon sequestration.interestingengineering+1

"We believe this easily applicable, risk-free environmental engineering strategy could be implemented at many places with real-world decarbonization outcomes," Silver said.wyss.harvard