Browsing by Author "Overa, Sean"
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Item A hybrid inorganic–biological artificial photosynthesis system for energy-efficient food production(Nature Food, 2022-06-23) Hann, Elizabeth C.; Overa, Sean; Harland-Dunaway, Marcus; Narvaez, Andrés F.; Le, Dang N.; Orozco-Cárdenas, Martha L.; Jiao, Feng; Jinkerson, Robert E.Artificial photosynthesis systems are proposed as an efficient alternative route to capture CO2 to produce additional food for growing global demand. Here a two-step CO2 electrolyser system was developed to produce a highly concentrated acetate stream with a 57% carbon selectivity (CO2 to acetate), allowing its direct use for the heterotrophic cultivation of yeast, mushroom-producing fungus and a photosynthetic green alga, in the dark without inputs from biological photosynthesis. An evaluation of nine crop plants found that carbon from exogenously supplied acetate incorporates into biomass through major metabolic pathways. Coupling this approach to existing photovoltaic systems could increase solar-to-food energy conversion efficiency by about fourfold over biological photosynthesis, reducing the solar footprint required. This technology allows for a reimagination of how food can be produced in controlled environments.Item Turning Carbon Dioxide into Sustainable Food and Chemicals: How Electrosynthesized Acetate Is Paving the Way for Fermentation Innovation(Accounts of Chemical Research, 2023-06-20) Crandall, Bradie S.; Overa, Sean; Shin, Haeun; Jiao, FengConspectus The agricultural and chemical industries are major contributors to climate change. To address this issue, hybrid electrocatalytic–biocatalytic systems have emerged as a promising solution for reducing the environmental impact of these key sectors while providing economic onboarding for carbon capture technology. Recent advancements in the production of acetate via CO2/CO electrolysis as well as advances in precision fermentation technology have prompted electrochemical acetate to be explored as an alternative carbon source for synthetic biology. Tandem CO2 electrolysis coupled with improved reactor design has accelerated the commercial viability of electrosynthesized acetate in recent years. Simultaneously, innovations in metabolic engineering have helped leverage pathways that facilitate acetate upgrading to higher carbons for sustainable food and chemical production via precision fermentation. Current precision fermentation technology has received much criticism for reliance upon food crop-derived sugars and starches as feedstock which compete with the human food chain. A shift toward electrosynthesized acetate feedstocks could help preserve arable land for a rapidly growing population. Technoeconomic analysis shows that using electrochemical acetate instead of glucose as a fermentation feedstock reduces the production costs of food and chemicals by 16% and offers improved market price stability. Moreover, given the rapid decline in utility-scale renewable electricity prices, electro-synthesized acetate may become more affordable than conventional production methods at scale. This work provides an outlook on strategies to further advance and scale-up electrochemical acetate production. Additional perspective is offered to help ensure the successful integration of electrosynthesized acetate and precision fermentation technologies. In the electrocatalytic step, it is critical that relatively high purity acetate can be produced in low-concentration electrolyte to help ensure that minimal treatment of the electrosynthesized acetate stream is needed prior to fermentation. In the biocatalytic step, it is critical that microbes with increased tolerances to elevated acetate concentrations are engineered to help promote acetate uptake and accelerate product formation. Additionally, tighter regulation of acetate metabolism via strain engineering is essential to improving cellular efficiency. The implementation of these strategies would allow the coupling of electrosynthesized acetate with precision fermentation to offer a promising approach to sustainably produce chemicals and food. Reducing the environmental impact of the chemical and agricultural sectors is necessary to avoid climate catastrophe and preserve the habitability of the planet for future generations.