【Frontiers of HaiChuan Chemical Technology】Seawater “turned into” bioplastics! Chinese scientists collaborate to solve the challenge of carbon capture from seawater

Thread Content

As the largest natural \"carbon sink\" on Earth, the oceans absorb more than a quarter of the carbon dioxide emitted by humans each year, thereby helping to mitigate global warming. However, ocean acidification caused by the continuous absorption of carbon dioxide by seawater poses a serious threat to the marine ecosystem balance. How to convert this carbon that has entered the ocean into resources usable by humans in order to mitigate ocean acidification is a common challenge in achieving the goals of a \"blue economy\" and \"dual carbon\" targets. On October 7, reporters learned from the University of Electronic Science and Technology that the National Key Laboratory of Quantitative Synthetic Biology at the Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, along with the team led by Gao Xiang from the Institute of Synthetic Biology, in collaboration with the team led by Xia Chuan from the University of Electronic Science and Technology, proposed and demonstrated for the first time an \"artificial ocean carbon cycle system\" based on a \"electrocatalysis + biocatalysis\" hybrid strategy. The relevant findings were published in the international academic journal Nature Catalysis. This system can capture CO2 from natural seawater and convert it into intermediates that can be used directly in biological manufacturing, which can then be further transformed into various high-value chemicals and materials. Using biodegradable plastic monomers as a model, this research holds the potential to provide a biomanufacturing platform for a wider range of products, including fuels, pharmaceuticals, and food ingredients. Professor Xia Chuan from University of Electronic Science and Technology, the project leader of the electrocatalysis+biocatalysis integrated system, explained that this achievement opens up new pathways for the sustainable utilization of marine carbon sink resources. It not only provides new solutions for addressing climate change, but also lays the essential technical foundation for the development of green and low-carbon new material industries, thereby promoting the high-value utilization of marine carbon resources. Solving the challenge of efficient carbon capture from seawater: The \"artificial ocean carbon cycle system\" proposed in this research creates a complete chain that ranges from \"carbon absorption from seawater\" to the production of materials and molecules. By utilizing a combined approach of electrocatalysis and synthetic biology, it successfully establishes a connection between carbon capture from seawater and subsequent biological transformations. Using biodegradable plastic monomers as an example, this approach forms an expandable platform that serves as a new model for interdisciplinary collaboration. The first key step of the research was carried out by the Xia Chuan team from the University of Electronic Science and Technology; they utilized electrocatalytic technology to achieve efficient carbon capture from seawater. To address challenges such as electrode passivation and salt deposition, the research team designed a new type of electrolysis device. Experimental results show that this device can operate continuously and stably in natural seawater for over 500 hours, with a carbon capture efficiency of more than 70%, while also producing hydrogen as a by-product. In terms of cost-effectiveness, the cost of capturing one ton of carbon dioxide is approximately $229.9, indicating good prospects for practical application. Furthermore, the research team successfully developed a highly active and selective bismuth-based catalyst (Bi-BEN) using a two-step approach; this catalyst enables the efficient conversion of captured carbon dioxide into formic acid through electrocatalysis. Continuous and stable operation of this system over 20 days allowed for the production of high-concentration pure formic acid solutions. The second key step in the research to create super cells that can \"consume\" formic acid and \"excrete\" plastic was led by the team led by Gao Xiang from the Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences; they used biocatalytic methods to convert formic acid solutions into biochemicals that can serve as alternatives to those derived from fossil fuels. Although formic acid is widely available, its biological toxicity makes it difficult for most microorganisms to utilize it efficiently. To address this challenge, Gao Xiang’s team developed a \"super cell\" capable of efficiently utilizing formic acid and converting it into plastic monomers. The research team selected the rapidly growing marine bacterium Vibrio natriegens as the host cell, and through long-term evolution in the laboratory as well as synthetic biology techniques, systematically restructured the bacterial gene circuits to successfully create \"engineered bacteria\" that can tolerate high concentrations of formic acid and use it as the sole carbon source for efficient growth and metabolism. This engineered bacterium is capable of precisely converting formic acid into succinic acid, the key monomer for synthesizing the biodegradable plastic polybutylene succinate (PBS), as well as lactic acid, the monomer for the biodegradable plastic polylactic acid (PLA). Gao Xiang (right), co-corresponding author of the paper, and Guo Mingming (left), co-first author of the paper, are discussing the experimental results. To verify the carbon flow within the entire system as well as its industrial feasibility, the researchers first used carbon isotope (13C) labeling experiments to confirm that the carbon atoms in the succinic acid molecules produced were derived from the carbon dioxide captured initially. On this basis, they carried out scale-up experiments in 1-liter and 5-liter fermenters, successfully transitioning the research from the laboratory flask scale to the pilot plant scale. It is worth noting that the production of lactic acid in the products during the experiments also opens up new possibilities for expanding the diversity of biodegradable plastics. From the laboratory to the industrial chain, a blueprint for \"green factories\" is taking shape. Currently, the research team has synthesized fully biodegradable PBS and PLA using synthetic bioplastic monomers, and has produced demonstration straw products, demonstrating the industrial feasibility of converting seawater into green materials. Researchers point out that PBS and PLA are merely demonstration examples of this biomanufacturing platform; through electrocatalysis and the modular design as well as combined optimization of metabolic pathways, this platform has the potential to be expanded to cover a wide range of products such as organic acids, monomers, surfactants, and nutritional ingredients, serving industries in areas such as materials science, chemistry, pharmaceuticals, and food processing. Gao Xiang, an associate researcher and co-leader of the project, said, “We aim to transform the abundant carbon resources in the ocean into green, high-value products, in order to achieve multiple goals such as carbon reduction, resource utilization, and industrial upgrading.” This research also provides important scientific and technological support for our country to implement the ‘dual carbon’ strategy and build a strong maritime nation. ” In the future, the research team plans to build integrated “green factories” in coastal areas. On the one hand, it relies on electrocatalytic devices to continuously capture carbon dioxide from seawater and convert it into formic acid. On the other hand, formic acid is efficiently converted into green plastic raw materials using engineered bacteria in a fermentation tank.