Scientists at The University of Manchester have achieved a significant breakthrough in using cyanobacteria-commonly known as "blue-green algae"--to convert carbon dioxide (CO2) into valuable bio-based materials.
Their work, published in Biotechnology for Biofuels and Bioproducts, could accelerate the development of sustainable alternatives to fossil fuel-derived products like plastics, helping pave the way for a carbon-neutral circular bioeconomy.The research, led by Dr Matthew Faulkner, working alongside Dr Fraser Andrews, and Professor Nigel Scrutton, focused on improving the production of citramalate, a compound that serves as a precursor for renewable plastics such as Perspex or Plexiglas. Using an innovative approach called "design of experiment," the team achieved a remarkable 23-fold increase in citramalate production by optimising key process parameters.
Why Cyanobacteria?
Cyanobacteria are microscopic organisms capable of photosynthesis, converting sunlight and CO2 into organic compounds. They are a promising candidate for industrial applications because they can transform CO2--a major greenhouse gas-into valuable products without relying on traditional agricultural resources like sugar or corn. However, until now, the slow growth and limited efficiency of these organisms have posed challenges for large-scale industrial use."Our research addresses one of the key bottlenecks in using cyanobacteria for sustainable manufacturing," explains Matthew. "By optimising how these organisms convert carbon into useful products, we’ve taken an important step toward making this technology commercially viable."
The Science Behind the Breakthrough
The team’s research centred on Synechocystis sp. PCC 6803, a well-studied strain of cyanobacteria. Citramalate, the focus of their study, is produced in a single enzymatic step using two key metabolites: pyruvate and acetyl-CoA. By fine-tuning process parameters such as light intensity, CO2 concentration, and nutrient availability, the researchers were able to significantly boost citramalate production.Initial experiments yielded only small amounts of citramalate, but the design of experiment approach allowed the team to systematically explore the interplay between multiple factors. As a result, they increased citramalate production to 6.35 grams per litre (g/L) in 2-litre photobioreactors, with a productivity rate of 1.59 g/L/day.
While productivity slightly decreased when scaling up to 5-litre reactors due to light delivery challenges, the study demonstrates that such adjustments are manageable in biotechnology scale-up processes.
By turning CO2 into something valuable, we’re not just reducing emissions-we’re creating a sustainable cycle where carbon becomes the building block for the products we use every day.
A Circular Bioeconomy Vision
The implications of this research extend beyond plastics. Pyruvate and acetyl-CoA, the key metabolites involved in citramalate production, are also precursors to many other biotechnologically significant compounds. The optimisation techniques demonstrated in this study could therefore be applied to produce a variety of materials, from biofuels to pharmaceuticals.By enhancing the efficiency of carbon capture and utilisation, the research contributes to global efforts to mitigate climate change and reduce dependence on non-renewable resources.
"This work underscores the importance of a circular bioeconomy," adds Matthew. "By turning CO2 into something valuable, we’re not just reducing emissions-we’re creating a sustainable cycle where carbon becomes the building block for the products we use every day."
What’s Next?
The team plans to further refine their methods and explore ways to scale up production while maintaining efficiency. They are also investigating how their approach can be adapted to optimise other metabolic pathways in cyanobacteria, with the aim of expanding the range of bio-based products that can be sustainably manufactured.This research is the latest development from the Future Biomanufacturing Research Hub (FBRH) and was completed in collaboration with the FlexBio scale-up facility at Heriot-Watt University.