IN BRIEF
Researchers rewired siderophore production in the marine bacterium Alteromonas macleodii.
The modification increased olivine dissolution 2.6-fold.
A pilot system using untreated seawater and more than 4 kg of olivine directly measured 0.50 g of CO2 removed from air per day.
WHY IT MATTERS
Enhanced rock weathering is attractive for carbon removal, but slow mineral dissolution limits practical throughput.
The important shift here is from potential chemistry alone to a continuous biological process with directly measured CO2 removal.
WHAT IS NOW POSSIBLE
A carbon-removal concept that was constrained by slow mineral weathering was demonstrated as a continuous biological reactor process with kilogram-scale mineral loading and directly measured CO2 removal.
WHAT MADE IT POSSIBLE
Synthetic biology made petrobactin production constitutive, preventing iron released from olivine from shutting down the process.
A continuous mineral reactor made it possible to test real seawater, a renewable feed and kilogram-scale mineral loading.
THE STORY
Olivine can convert atmospheric CO2 into stable bicarbonate as it dissolves, but the reaction is slow. Bacteria can accelerate dissolution with iron-binding siderophores, yet natural regulation shuts their production down when iron becomes available.
The team modified Alteromonas macleodii to keep the petrobactin pathway active. The engineered strain increased olivine dissolution 2.6-fold.
The process was then moved into continuous pilot reactors containing more than 4 kg of olivine and untreated Boston Harbor seawater. Alkalinity generation corresponded to 0.50 g of CO2 per day directly removed from air.
The life-cycle analysis also shows that the carbon balance remains favorable only with low-emission feedstocks and limited cell replenishment.
WHAT WE KNOW
CO2 removal was directly measured in the pilot system. [1]
The peer-reviewed study combines genetic engineering, continuous experiments and life-cycle analysis.
WHAT WE DON'T KNOW
It is not yet known whether performance, safety and carbon balance will hold at industrial scale.
The work does not demonstrate open-environment deployment or climate-significant removal volumes.
WHAT HAPPENS NEXT
Scale and extend reactor operation while controlling biofilms, nutrients and microbial replenishment.
Test full carbon balance and reliability in larger pre-commercial systems.
SOURCE TRACE
Engineering Alteromonas macleodii for enhanced constitutive siderophore production increased the olivine dissolution rate 2.6-fold.
Pilot-scale continuous reactors weathered more than 4 kg of olivine in unprocessed seawater and directly measured removal of 0.50 g CO2 per day from air through alkalinity generation.
The study's life-cycle analysis found that renewable feedstocks and low engineered-cell replenishment are critical conditions for net CO2 removal at larger scale.
SOURCES
- Engineered bacterial siderophore production accelerates rock weathering for carbon removalOpen source
CURRENT EVIDENCE
PEER-REVIEWED
Pilot-scale continuous mineral bioreactor using more than 4 kg of olivine and unprocessed seawater
WHAT WOULD CHANGE THIS?
- If larger independent tests show that energy, feedstocks, cell replenishment or biological control erase net CO2 removal, the climate significance should be downgraded.