This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Rock weathering, the breakdown and dissolving of rocks and minerals caused by their exposure to water, air and biological life, is a major regulator of Earth's atmospheric CO2 levels and climate. Throughout Earth's history, rock weathering has been faster during warm periods with increased atmospheric CO2 levels.
Dissolved minerals ultimately wash into the ocean, where they draw CO2 from the atmosphere and cool the planet again. While this thermostat is responsible for the temperate climate we enjoy on Earth, the weathering cycle occurs over hundreds of thousands of years. In search of climate solutions, scientists have asked whether the rock weathering cycle could be sped up, resulting in a number of new companies pursuing enhanced rock weathering (ERW).
By scattering crushed silicate rocks on agricultural surfaces or into water, they aim to pull excess CO2 out of the atmosphere. Although this strategy is generally safe and environmentally friendly, it is still too slow to affect the global carbon balance or to be economically viable on an industrial scale. Now, a collaborative research team at the Wyss Institute at Harvard University, Harvard Medical School (HMS)'s Department of Systems Biology and the Stanford Doerr School of Sustainability, led by Wyss Institute Founding Core Faculty member Pamela Silver, Ph.D., and Wyss Institute Associate Faculty member Michael Springer, Ph.D., has engineered a potential solution to this problem.
The research team, spearheaded by first author and chemical engineer Neil Dalvie, Ph.D., genetically engineered Alteromonas macleodii, a widespread marine bacterium, to produce much higher amounts of so-called siderophores, molecules that extract iron from silicate minerals. In customized bioreactors with a continuous flow of seawater, the engineered bacterium sped up the weathering of the silicate mineral olivine by 2.6-fold, boosting the amount of CO2 removed from the air. Their findings are published in Nature Biotechnology.
"Our study embraces the concept of biologically inspired engineering and how synthetic biology can be applied to enhance normal climate-regulating processes, which ultimately could have a positive impact on our planet," said Silver, who also is the Elliot T. and Onie H. Adams Professor of Biochemistry and Systems Biology at HMS and, together with Springer, founded the Synthetic Biology Hive at HMS. "We believe this easily applicable, risk-free environmental engineering strategy could be implemented in many places with real-world decarbonization outcomes." During natural rock weathering, silicate minerals like olivine dissolve to release primarily magnesium (Mg), iron (Fe) and silicate (SiO4), trapping atmospheric CO2 in the water as bicarbonate (HCO3-).
MgFeSiO4 + 4CO2 + 4H2O → Mg2+ + Fe2+ + H4SiO4 + 4HCO3− Specifically, the released iron is not soluble when exposed to the atmosphere. Instead, it covers the mineral surface as rust, slowing down the entire process. By producing siderophores, bacteria can capture, solubilize and take up oxidized (rusted) iron to sustain their own growth.
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