' The greatest threat to our planet is the belief that someone else will save it. '
— Robert Swan
CUG-China's project—an innovative approach designed to engineer
Acidithiobacillus ferrooxidans for efficient conversion of solar energy into chemical energy and CO₂ fixation—has been closely connected to the global community since its inception. We recognize that true innovation emerges not only from the laboratory but also from deep dialogues with society and an acute understanding of real-world challenges.
1. Problem Orientation: Facing the Dual Crisis of Climate and Energy
Human society is currently under the dual pressure of a climate crisis and an energy crisis. On one hand, excessive CO₂ emissions have led to global warming and frequent extreme weather events. By analyzing data on global temperature and CO₂ emissions from 1980 to 2024, we observed a continuous upward trend in annual temperature relative to the 1951–1980 mean, accompanied by steadily increasing CO₂ emissions in recent decades.
On the other hand, renewable energy sources such as solar and wind power, while highly promising, suffer from intermittency and instability. This results in a substantial amount of electricity being wasted due to storage limitations—forming a critical bottleneck in the widespread adoption of clean energy. Therefore, our central goal is to efficiently and stably convert difficult-to-store electrical energy into easily storable and transportable chemical energy, while simultaneously achieving CO₂ fixation.
Building upon last year's foundation, we selected Acidithiobacillus ferrooxidans as our chassis organism, a decision supported by both scientific rationale and project continuity.
Natural Advantages: A. ferrooxidans is a chemolithoautotrophic bacterium capable of using CO₂ as its sole carbon source and deriving energy from the oxidation of ferrous iron or sulfide. This provides a natural biological basis for CO₂ fixation.
Extremophilic Chassis: Its acidophilic nature (pH < 2) and mesophilic growth conditions create a naturally sterile reactor where most contaminant microbes cannot survive. This minimizes bio-contamination risk and offers a clean culture environment suitable for industrial applications.
Project Continuity and Upgrade: Last year, we successfully established stable culturing procedures and explored its potential in biomining. This year, we strategically upgraded the project from 'enhancing biomining' to 'enhancing electricity uptake'—leveraging synthetic biology to strengthen the bacterium's ability to use electricity for carbon fixation.
3. Expected Outcomes: What Do We Aim to Achieve?
1. Develop an efficient and stable Microbial Electrochemical Synthesis (MES) system：successfully converts electrical energy generated by solar panels into valuable chemicals such as glycerol through the engineered A. ferrooxidans.
2. Deliver dual environmental benefits: capturing industrial CO₂ emissions to support carbon neutrality, and storing surplus renewable electricity in chemical form to enhance clean energy utilization efficiency.
3. Demonstrate the industrial potential of extremophilic chassis microbes, identifying key challenges in scale-up and proposing feasible solutions bridging laboratory research and industrial application.
4. Core Pathway: Systematic Design and Multidimensional Optimization
Our work is not only rigorous in science but also grounded in social responsibility, ethical legitimacy, and alignment with stakeholder values. To systematically guide this holistic approach, we developed the H.E.A.R.T. Framework (Harmony-Driven Envision, Adaptation, Realization & Transformation). This closed-loop framework emphasizes continuous dialogue, dynamic adjustment, and value co-creation to guide responsible innovation.
H – Harmonize with Stakeholders
Objective: Proactively engage with diverse stakeholders through equitable and respectful dialogue beyond the laboratory.
Practice: We conducted interviews with industrial partners to identify bottlenecks such as culturing cost and scale-up effects, consulted interdisciplinary experts for insights into abiotic microenvironmental regulation, and organized public outreach to promote understanding of synthetic biology and carbon neutrality.
Academic Collaboration:
Our interview with Professor Dong Yiran provided critical interdisciplinary insights, emphasizing the importance of system-level optimization beyond microbial genetic modification—informing our integrated system design.
Interview with Professor Dong Yiran
Research Areas: Environmental biogeochemistry, cultivation and physiological characteristics of atypical metal-metabolizing microorganisms, and bioremediation of groundwater and soil contaminants.
Key Insights and Reflections
Harvest:
1.Ideas and solutions to experimental problems
2. We must not be limited solely to the genetic modification of microorganisms themselves; instead, we need to design and optimize from the perspective of the entire system.
3. Solving biological problems sometimes requires the use of non-biological methods—for example, geological mineral materials have unique value in regulating microenvironments.
Impact: This discussion greatly enriched our project’s knowledge base and future technical roadmap. It provided us with new methods for deeper investigation and optimization, expanding our thinking beyond single-path biotechnological modifications. Her insights opened interdisciplinary possibilities and offered valuable theoretical references and alternative strategies for future research directions.
1. Besides carbon dioxide, what are the main greenhouse gases, and what are their sources?
• Apart from CO₂, the main greenhouse gases include methane (CH₄) and nitrous oxides (N₂O, NO). Methane primarily comes from methanogenic microorganisms that thrive in anaerobic environments like wetlands and groundwater. Although nitrous oxides occur in smaller amounts compared to CO₂, their greenhouse effect is much stronger, so they must not be overlooked.
2. To what extent can technological advancements (e.g., new energy sources, carbon capture technologies) help mitigate global warming?
• Part of the problem can be solved through technology. Some technologies already work well in the lab, but their commercialization remains limited. In carbon capture the main field of my research, for example, our country has made notable progress with CCUS (Carbon Capture, Utilization, and Storage) technologies. Traditional CCS systems have high technical and cost barriers, mainly due to the collection and fixation process. So, while these technologies are promising, they either need technical breakthroughs or strong economic support to become widely adopted.
3. What types of microorganisms can be used for carbon fixation?
• We should keep an open mind about this. While many associate CO₂ utilization with it being a carbon source, current research has advanced further, like transforming CO₂ into high-value-added products. For example, some studies have converted CO₂ into butanol in recent years. Some biodegradable polymers were just made from CO₂-derived high-carbon compounds.
4. What’s your view on the potential of autotrophic microorganisms for carbon fixation?
• One of the popular approaches now is using algae to produce bio-based materials or biofuels. Its advantage is that it requires no extra energy input since algae can naturally convert light energy into chemical energy. However, issues like low yield, instability, and contamination control still need to be solved. Therefore, the success of such technologies depends not only on scientific development but also on market readiness and public acceptance, these also the points that I consider to be critical.
5. We plan to enhance the key enzyme RuBisCO in the CBB cycle. But since acidophiles operate in low pH environments, their enzyme activity might be limited. Do you have any suggestions for improving stability?
• Microorganisms have mechanisms of directed evolution. You could simulate natural selection and screen for strains with higher enzyme activity. That would allow you to obtain variants with improved stability and performance.
6. Our system aims to convert solar energy to electricity, then use microbes to produce glycerol. From your professional perspective, what are the main technical risks, and how could we optimize energy transfer efficiency?
• If the goal is commercialization, the main risks are cost and efficiency. In a laboratory context, efficiency is the primary issue. You could try optimizing microbial growth and culture conditions—looking for substrates that are more efficiently utilized or less toxic. Improving electron yield, light distribution, CO₂ fixation efficiency, glycerol purity, and production energy balance can all enhance energy transfer efficiency.
7. Acidithiobacillus ferrooxidans may produce sulfuric acid when oxidizing ferrous iron, leading to further acidification. Could this inhibit glycerol synthase? Are there any in-situ pH control strategies?
• It might have an inhibitory effect, but that depends on specific experimental results. Intracellular pH is usually maintained within a safe range, so the issue is more about the external environment. In-situ pH regulation is quite complex, so I would suggest switching to a different enzyme first to ensure stable bacterial growth.
8. In your team’s research on geological CO₂ sequestration, have you found that minerals play a catalytic or buffering role in microbial carbon fixation? Could these be coupled with biological systems to improve efficiency?
• Yes, minerals play a significant and multifaceted role. They act as natural pH buffers and provide ‘refuge spaces’ for microorganisms through their microfissures. Minerals can indeed couple with biological systems—especially in acidic environments, where their dissolution helps buffer pH and stabilize microbial habitats. For instance, we found that quartz sand can protect microbes in strong acid conditions by reducing environmental stress and maintaining microbial activity, it can also trigger a chain reaction.
2.Industrial Collaboration: Through visits to Water Nation Environmental Technology Co., Ltd., we gained firsthand knowledge of the challenges facing engineered microbial cultivation at industrial scale, such as high cost of operation and complexity of process control and uncertainty of amplification effect. These first-hand information sources have anchored the realistic coordinates for our technology development.
Water Nation Environmental Technology Co., Ltd.
Main Business:
R&D, production, sales, and service of microbial agents for wastewater treatment.
Harvest:
The 'double-edged sword' nature of extreme microorganisms must be systematically weighed.
Industrialization must follow a 'scenario-driven' logic and cannot be detached from real-world environments and market needs.
True productization does not start from 'technical feasibility' but from 'market demand,' encompassing the full lifecycle loop of validation, scaling, delivery, and feedback.
Impact:
This has provided valuable industrialization perspectives and engineering thinking for the CUG-China 2025 project. The company emphasizes 'market demand-driven R&D,' prompting us to reevaluate the technical route from practical dimensions such as glycerol market saturation, extreme microorganism preservation stability, and equipment corrosion-resistant costs. Their '5L → 50L → 500L/5-ton' three-stage scaling process has made us realize that the gap between laboratory results and industrialization must be bridged through pilot-scale validation. This exchange has greatly enhanced our understanding of 'responsible innovation,' shifting the project’s focus from 'possible' to 'usable, producible, and implementable.'
Future Plans in Synthetic Biology
• Our company is already preparing for synthetic biology-related technical development. The synthetic biology lab has been officially established, and some research equipment has started operation. Although we currently rely on traditional strain screening methods, we plan to advance to the molecular level in the near future, applying synthetic biology approaches for more efficient strain selection.
We plan to use Acidithiobacillus ferrooxidans as a chassis organism, since it resists contamination under strong acid (pH < 2). In actual production, has your company considered using extreme environments to reduce sterilization costs?
• Absolutely! Although we mainly use neutral autotrophs like nitrifying bacteria, we fully understand your approach, extreme conditions themselves act as a natural barrier. In theory, your strong-acid system barely requires sterilization, which is crucial for lowering industrial costs. Sterilization is one of the biggest energy and cost burdens in traditional fermentation.
Are extremophiles more difficult to culture and store?
• That’s precisely the main challenge in productization. For example, strain preservation — if activity decays too fast under low or room temperature during use, the application performance will suffer. Therefore, during screening, we comprehensively evaluate growth rate, stress resistance, fermentation performance, and storage stability. For your acidophilic strains, successful commercialization will require developing specific protectants or complementary stabilization processes.
Our design is a multi-step system: 'Electrical energy → CO₂ → Glycerol.‘ What were your biggest challenges when scaling up from lab cultures to 50 L, 500 L, or even ton-scale fermenters?
• The amplification effect is very pronounced. Parameters optimized in a 5 L lab bioreactor need to be re-tuned at 50 L, pH control, oxygen supply, and feeding strategy all change. At the 5-ton industrial scale, mass transfer and mixing become new issues. We recommend considering reactor materials early. For instance, Hastelloy for acid resistance. Since standard stainless steel corrodes rapidly below pH 2, which can drastically raise equipment costs.
What is the process for industrial-scale production of your company’s products?
• Our industrialization pipeline starts from market demand. Functional strains are first isolated from natural environments, such as soil and water, followed by tube-scale preliminary screening and shake-flask rescreening. Then, growth and metabolism parameters are optimized in 5 L fermenters. Mid-scale validation is conducted in 50 L pilot reactors, focusing on mass transfer, oxygen supply, and process stability. These 50 L parameters directly integrate into the production line at our Ezhou factory, enabling scale-up to 500 L and 5-ton fermentation. Throughout the process, we comprehensively evaluate growth rate, stress resistance, fermentation efficiency, and preservation stability to ensure reliable performance and sufficient shelf life in real-world applications.
From lab to product, how do academic and industrial R&D priorities differ?
• Universities pursue ‘single performance optimization’. For example, maximum yield, while companies pursue 'overall performance balance’. A strain may have high yield but poor preservation, or excellent stress tolerance but slow growth. So we must weigh these trade-offs quantitatively. For your project to succeed in real application, you’ll need to incorporate engineering metrics such as cost, stability, and manufacturability from the earliest stages.
During our communications with the company, we were inspired by their product R&D process to establish an R&D workflow that is more relevant to the projects of our laboratory. We strictly adhere to this workflow and advance step by step as required. A diagram is attached below for your reference.
This flowchart systematically outlines the full-lifecycle management path from market demand to product delivery, covering key stages including 'market research → project initiation → strain acquisition and culture optimization → experimental verification → fermentation and storage process design → delivery to production line → stability and efficacy verification → feedback and improvement'. It adopts a market-oriented and data-driven R&D logic, places greater emphasis on product quality stability and technical convertibility, and provides process references and engineering thinking paradigms for scientific research projects to move from the laboratory to industrialization.
3.Public Engagement:
We have carried out a series of science popularization activities (Education) targeting groups ranging from kindergarten to university students of all academic stages, as well as the general public in communities. Through interactive experiments, model demonstrations and accessible lectures, we have popularized knowledge about synthetic biology, carbon neutrality and renewable energy, while also collecting the public's ethical concerns and expectations regarding emerging biotechnology.
This process deepened our understanding of market needs, technical boundaries, and social expectations.It has laid a solid foundation for the responsible innovation of the project.
' Mutual Benefit Oasis Needs You ' – We start with listening and end with co-construction.
E – Envision Futures
Based on stakeholder feedback, we simulated potential multidimensional impacts of our project—assessing environmental, social, and economic implications while systematically evaluating the engineered A. ferrooxidans as our chassis.
Advantages:
The acidophilic, chemolithoautotrophic nature of A. ferrooxidans allows growth in pH < 2 environments, minimizing contamination and reducing operational complexity and cost which also provides biosafety assurance for long-term, stable, and continuous operation. Its innate extracellular electron transfer (EET) ability bridges electrochemical systems and biological carbon fixation.
Challenges:
The 'double-edged sword' nature of extremophiles is equally prominent. First, their cultivation and storage require harsh conditions—including the maintenance of a strongly acidic environment and specific inorganic energy sources. This not only increases the difficulty of laboratory operations but also directly drives up the operating costs during industrial scale-up. Second, as Professor Dong has pointed out, this bacterium produces sulfuric acid during the oxidation of ferrous iron; this further intensifies the acidification of the system and may inhibit the activity of heterologous proteins. Third, the genetic manipulation tools for extremophiles are relatively scarce, with low gene editing efficiency and unstable expression systems, creating technical obstacles to the construction of synthetic pathways.
Based on the comprehensive understanding of chassis strains, we further conduct scenario simulations:
Positive Future Scenario:
If we successfully overcome the cultivation and expression bottlenecks, the project can achieve dual environmental benefits — capturing CO₂ from industrial emissions and converting intermittent renewable energy into chemical energy that is easy to store and transport. This system is expected to provide unique value in distributed CO₂ conversion scenarios while contributing to several United Nations Sustainable Development Goals, such as Goal 7 (Affordable and Clean Energy), Goal 9 (Industry, Innovation, and Infrastructure), Goal 12 (Responsible Consumption and Production), and Goal 13 (Climate Action).
Risk Scenario:
The primary risks identified include: cost and efficiency challenges during commercialization; biosafety concerns related to extreme microorganisms in uncontrolled environments; and the market saturation risk of glycerol as a bulk chemical. If the strain stability is insufficient, glycerol yield is too low, or cultivation costs cannot be reduced, the project may struggle to bridge the 'lab-to-pilot scale' gap. Additionally, while the risk of biological contamination is low, public perception of 'genetically engineered extreme microorganisms' may be biased, requiring transparent communication and educational guidance.
Output:
In response, we have learned from the project processes of Water Nation Environmental Technology Co., Ltd. and have formulated a more pragmatic and responsible roadmap. We have clearly identified the technological nodes that need to be prioritized and have established a sustainability evaluation framework guided by the SDGs.
Foreseeing is not about predicting, but about choosing the most responsible path for ' harmony. '
A – Adapt the Design
Objective: Integrate insights from 'Envision' and 'Harmonize' phases back into core design, fostering co-evolution between technological and social systems.
1.Chassis Engineering (Why & How): Wild-type A. ferrooxidans is not an efficient 'electricity consumer'.
How: We designed a cyclic di-GMP synthase module to enhance EET capacity. This enables it to efficiently 'uptake' electrons from the electrode to drive the Calvin cycle, thereby increasing the efficiency and rate of carbon dioxide fixation.
2.Energy Carrier Selection (Why Glycerol?):
Why:We need a chemical energy carrier that is stable, has high energy density, and is easy to store and transport. Glycerol is an ideal choice. It is not only a crucial chemical raw material, but its molecular structure also makes it suitable as an energy storage medium. Converting electrical energy into glycerol can perfectly address the drawback of 'difficult storage' associated with new energy sources.
How:We will construct or optimize the metabolic pathway from central carbon metabolism to glycerol synthesis in the modified bacterial strain, guiding the fixed carbon flow toward glycerol production.
Output:
Iteratively optimized bacterial strains, reactors, and system integration solutions.
True innovation is the continuous reshaping of oneself in response to feedback from the world.
R – Realize & Share Transformation
Objective: To put the adapted plan into practice, implement the theoretical model, and feed back knowledge, tools, and concepts to society, forming a positive cycle.
Practice:
1.Model Implementation: Construct and verify a microbial electrochemical synthesis (MES) system for the 'solar energy → electrical energy → chemical energy' conversion process in the laboratory.
2.Educational Empowerment: We have developed a large number of reproducible science popularization and educational activities as well as games, which have been demonstrated in various primary schools, middle schools, universities, and community events. These initiatives aim to inspire the public's interest in and understanding of how synthetic biology can address global challenges.
3.Collaborative Co-creation: We actively communicate with other iGEM teams at home and abroad, conducting multiple online and offline cooperative exchanges. We share our experiences and challenges in the fields of extremophile chassis and electrosynthesis to jointly advance the development of these domains.
4.Sustainable Contribution: The project design explicitly aligns with multiple United Nations Sustainable Development Goals (SDGs). Based on this, we have compiled a detailed sustainability assessment report that systematically elaborates on the project's potential contributions to Goal 4 (Quality Education), Goal 7 (Affordable and Clean Energy), Goal 8 (Decent Work and Economic Growth), Goal 9 (Industry, Innovation and Infrastructure), Goal 10 (Reduced Inequalities), Goal 12 (Responsible Consumption and Production), and Goal 13 (Climate Action).
Output: Transformation is not only about the implementation of technology, but also about the transmission and resonance of value.
Transformation is not only the implementation of technology but also the transmission and resonance of value.
T – Tune Back to Harmony
Objective: Reassess whether the project truly promotes harmony between humanity and nature, and identify new opportunities for collaboration.
Closed-Loop Evaluation: We analyzed prototype performance data, educational feedback, and partner suggestions to evaluate the project's ethical and sustainable integrity.
New beginning: Based on these results, we identified new collaboration prospects—such as downstream glycerol applications—and defined challenges for the next iteration of the H.E.A.R.T. cycle.
Harmony is not an endpoint but a continuous direction of recalibration.
CUG-China 2025's scientific exploration beats to the rhythm of responsibility, dialogue, and harmony. Rooted in real-world challenges, empowered by synthetic biology, and guided by systems engineering, our project seeks to open a harmonious path toward a 'reciprocal oasis' at the intersection of climate and energy.
