Plastic bottles recycled into Parkinson's drug using bacteria

University of Edinburgh researchers have used bacteria to turn plastic waste into a Parkinson's drug, advancing a new approach known as "bio-upcycling".

The University of Edinburgh biotechnology researchers successfully synthesised the drug L-DOPA, also known as Levodopa, from the raw ingredient of post-consumer waste plastic, in a process they say is more sustainable than relying on pharmaceuticals' usual feedstock of fossil fuels.

The process involved breaking down polyethylene terephthalate (PET), the plastic widely used in food and drink packaging, and feeding it to genetically engineered E. coli bacteria, which built it back up again with a different molecular structure.

The researchers believe it is the first time a natural, biological process has been used to turn plastic waste into a medication for a neurological disease.

The method constitutes a type of bio-upcycling – an emerging field that uses microbes and enzymes to convert waste into higher-value products.

Bio-upcycling has particularly focused on plastic waste due to the finite nature of the material's crude oil feedstock and the insufficiencies in its recycling, which have seen plastic pollution become a major environmental and public health issue.

With bio-upcycling, microorganisms are engineered with special enzymes that enable them to sever the super-strong links between molecules in plastic – similar to what happens naturally with the ideonella sakaiensis bacterium, found in 2001 outside of a recycling plant in Japan – or to synthesise new links once it is broken down.

For the L-DOPA project, the researchers used a mix of chemical and biological processes, taking PET that had been chemically depolymerised into molecules of terephthalic acid and then using engineered bacteria to transform these molecules into L-DOPA through a series of four enzymatic reactions triggered through seven genes.

Proponents of bio-upcycling believe that it could be used to replace not just the medicines that are currently synthesised from petrochemicals but also substances such as flavourings, fragrances, cosmetics, animal feed and fuel.

"This feels like just the beginning," said University of Edinburgh professor Stephen Wallace, who led the research. "If we can create medicines for neurological disease from a waste plastic bottle, it's exciting to imagine what else this technology could achieve."

"Plastic waste is often seen as an environmental problem, but it also represents a vast, untapped source of carbon," he continued. "By engineering biology to transform plastic into an essential medicine, we show how waste materials can be reimagined as valuable resources that support human health."

Wallace's previous research at the university has included synthesising the flavouring vanillin from plastic waste – an achievement that designer Eleonora Ortolani built on in 2023 to make an ice-cream too experimental to eat.

The research has continued since then, and the researchers' have detailed their work on the L-DOPA synthesis in a paper published in the peer-reviewed journal Nature Sustainability today. Their next step will be to advance the technology towards industrial application.

It is unknown if bio-upcycling will ever be able to be applied to vast quantities of plastic waste at a time. For this reason, anti-plastic activists often do not see it as a solution for the urgent problem of plastic pollution.

Parley for the Oceans founder Cyrill Gutsch is one of these, having previously urged designers to continue to work on reducing the use of plastic rather than putting their hopes on a miracle.

The top photo is courtesy of Shutterstock.

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