About This Project
We propose that bacterial siderophores could accelerate mineral weathering reactors as an additive. Our data suggests that the requirement for siderophores to accelerate mineral dissolution may depend on reactor conditions and change over time. Using engineered bacterial strains, we will produce enough siderophores to perform extended continuous weathering experiments (over two weeks). The resulting data will inform a technoeconomic analysis and establish goals for further bioengineering.
Ask the Scientists
Join The DiscussionMotivating Factor
Atmospheric carbon dioxide removal and point-source carbon capture technologies are well-accepted as being necessary for meeting climate goals [1]. Weathering of alkaline minerals in the environment naturally generates alkalinity that draws ~0.3 GtCO2/yr from the atmosphere and converts it to solid carbonates or (bi)carbonates which are transported to the ocean and stably stored [2][3]. Enhanced rock weathering (ERW) technology seeks to accelerate alkaline mineral dissolution for carbon storage by grinding minerals to increase reactive surface area and exposing them to weathering conditions [4][5]. A core challenge of ERW is cost-effectively increasing mineral dissolution kinetics to enable scaling [6].
Specific Bottleneck
Dissolution of alkaline minerals may be limited by several chemical phenomena, including surface passivation by silica byproducts [7] or insoluble iron-oxides [8]. This proposal will focus on chelation and solubilization of iron oxides, which has been demonstrated to accelerate mineral weathering in marine and terrestrial settings. Siderophores, secondary metabolites secreted by bacteria to solubilize and harvest iron [9], have been demonstrated to accelerate the dissolution of the silicate mineral olivine [10]. Bacteria only produce siderophores under iron-limited conditions, however [11]. In their original study demonstrating acceleration of olivine dissolution, Torres et al. predicted that this natural physiology may limit the utility of siderophores at large scales [10].
Actionable Goals
Further experiments are needed to understand the utility of bacterial siderophores to accelerate mineral dissolution in industrial settings. While initial experiments were conducted in batch formats, industrial weathering processes are likely to operate continuously. Siderophore-mediated weathering should be evaluated in continuous formats, therefore, ideally for long times. Additionally, iron-oxide passivation is not the only mechanism known to slow mineral dissolution. Experiments should identify the process conditions in which siderophores are most effective at accelerating dissolution to understand how siderophore might work in cooperation with other catalysts for dissolution [12]. Finally, process designs should be proposed for application of siderophores for acceleration of weathering. Basic technoeconomic analysis should compare the predicted cost of siderophore production at large scales with the benefit from accelerated weathering.
Budget
The budget funds personnel and supplies for proposed experiments.
Meet the Team
Team Bio
Advisers at Harvard Medical School: Professor Pamela Silver, Professor Michael Springer
Industrial collaborators: Dr. Martin Van Den Berghe (Cytochrome), Dr. Nate Walworth (Scape)
We have worked informally for two years with Dr. Van Den Berghe and Dr. Walworth, who are developing prototype mineral reactors. Dr. Van Den Berghe is an expert in biogeochemical analysis and helped guide the construction of experimental platforms that are relevant to larger scales.
Neil Dalvie
I am a chemical engineer and a postdoctoral fellow in the Synthetic Biology Hive at Harvard Medical School. As an undergraduate at Northwestern, I gained a foundational knowledge in the logic and techniques of molecular biology from Professor Josh Leonard. In graduate school at MIT, I worked with Professor J. Christopher Love to enable low-cost manufacturing of vaccines and antibodies in yeast. I performed both protein and cell engineering and learned from biologists and bioengineers at MIT’s Koch Institute. During the COVID-19 pandemic, I led a small team in the rapid development of a vaccine candidate. Our process was implemented at scale at the Serum Institute of India, the world’s largest vaccine manufacturer, and the product was deployed in the clinic in Australia and Zimbabwe.
After graduate school, I received a Schmidt Science Fellowship to “pivot” my research. I joined the Synthetic Biology Hive to study the application of microorganisms to accelerate rock weathering. After two years learning geochemistry, marine biochemistry, and environmental microbiology, I established a unique experimental platform that enables coupled measurement of cell state and mineral dissolution rates. This will guide the design of mineral seawater bioreactors in the industry.
Experimental precision routinely deployed for the development and manufacture of medicines is missing from the development of environmental engineering processes. Conversely, the scale and cost of manufacturing of high-value products could be transformed by environmental microbiological discoveries. I envision a research program in bio-geo-chemical engineering to rigorously study continuous mineral processing and the production and application of siderophores. We will translate our work alongside large and small process engineering companies.
Google scholar: https://scholar.google.com/citations?user=wDIM6y0AAAAJ&hl=en&oi=ao
Website: https://www.neildalvie.com/
Additional Information
This problem statement was adapted from the statement “Design, TEA, and LCA of reactor-based bio-enhanced rock weathering” by Paul Reginato, Pritha Ghosh, Nathan G. Walworth, and Martin Van Den Berghe. The statement was adapted to specify the scope of the project focused on siderophore-mediated rock weathering.
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