Transforming carbon dioxide into renewable plastics

Scientists at the University of Manchester have made a breakthrough in using cyanobacteria, commonly known as blue-green algae, to convert carbon dioxide (CO2) into valuable bio-based materials. Their findings could advance sustainable alternatives to fossil fuel-derived products, such as plastics crucially necessary for life in the modern world, supporting a carbon-neutral circular bioeconomy.

The research was published in the Biotechnology for Biofuels and Bioproducts journal and led by Dr. Matthew Faulkner, Dr. Fraser Andrews, and Professor Nigel Scrutton. As reported on by the Phys.Org publication, they focused on enhancing the production of citramalate—a compound used to manufacture renewable plastics like Perspex or Plexiglas. Using a technique called "design of experiment," the team achieved a 23-fold increase in citramalate production by optimizing key parameters, such as light intensity and CO2 concentration.

Cyanobacteria are ideal for industrial applications due to their ability to photosynthesize, converting sunlight and CO2 into organic compounds without relying on traditional agricultural inputs like sugar or corn. Despite their potential, challenges such as slow growth and limited efficiency have hindered large-scale use. The team addressed these bottlenecks, working with the cyanobacterium Synechocystis sp. PCC 6803, and demonstrated significant improvements in converting carbon into useful products.

The breakthrough was achieved by fine-tuning how cyanobacteria produce citramalate in bioreactors. Initial experiments yielded small amounts, but the design-of-experiment approach allowed researchers to systematically explore the interaction of factors affecting production. In 2-liter photobioreactors, they achieved citramalate production levels of 6.35 grams per liter (g/L) at a productivity rate of 1.59 g/L/day. Although scaling up to 5-liter reactors led to slightly reduced productivity due to light distribution issues, the results show that such challenges are manageable in larger-scale biotechnology.

The implications extend beyond plastics. Pyruvate and acetyl-CoA, metabolites involved in citramalate production, are precursors for a wide range of valuable compounds, including biofuels and pharmaceuticals. The optimization techniques used in this study could potentially be applied to produce other bio-based materials, enhancing carbon capture and utilization to mitigate climate change and reduce dependence on fossil fuels.

“This work underscores the importance of a circular bioeconomy,” said Dr. Faulkner. “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 everyday products.”

Looking ahead, the team plans to refine their methods, improve scaling efficiencies, and adapt their approach to optimize other metabolic pathways in cyanobacteria. Their goal is to expand the range of bio-based products that can be sustainably manufactured, contributing to global efforts to combat climate change and establish a resource-efficient bioeconomy.

This research represents a significant step toward making cyanobacteria-based manufacturing commercially viable and showcases the potential of innovative biotechnologies to create a sustainable, carbon-neutral future.

By Nazrin Sadigova