Engineered Bacteria Make Rock Dissolve Faster to Pull CO2 From the Air

Researchers at Harvard's Wyss Institute have engineered a marine bacterium to make the mineral olivine dissolve faster, and measured carbon dioxide being pulled out of the air in a pilot-scale tank as a result. Their paper was published Aug. 28, 2026, in Nature Biotechnology and is open access.

Olivine generates alkalinity as it dissolves, converting atmospheric CO2 into stable bicarbonate ions. That reaction is the basis of enhanced weathering, a carbon-removal approach the authors note has been hard to measure in field trials, where crushed rock spread on soils or coastlines weathers slowly.

Alteromonas macleodii, the marine bacterium used here, secretes iron-grabbing molecules called siderophores, which pull iron oxides off the mineral surface and keep dissolution going. Normally, the bacterium's own genetic regulation shuts that production down inside a reactor because the dissolving olivine supplies enough iron. Neil C. Dalvie and colleagues, with co-authors at Harvard Medical School and Stanford, put the siderophore genes under an always-on promoter. The rewired strain gave "a 2.6-fold increase in the rate of olivine dissolution," the paper states, a factor of 2.6 plus or minus 1.0 measured against reactors holding no cells. The unmodified strain was not significantly faster than that control.

The team then ran continuous pilot-scale reactors on unprocessed seawater and a renewable acetate feedstock over 4 kg of olivine. In the reactors with engineered cells, they "directly measured removal of 0.50 g CO2 per day from the air through alkalinity generation." That is a measurement inside a pilot reactor, not from a deployed system.

The study's life-cycle analysis states that renewable feedstocks and minimal replenishment of the modified cells are critical to achieving net CO2 removal at scale, a condition the authors identify rather than a result they demonstrate. The industrial reactor they model for that analysis holds roughly 150 metric tons of olivine sand under 0.3 meters of stirred seawater.