Paracetamol—the pain and fever reliever we commonly use—has traditionally been produced from petroleum-based raw materials. However, scientists from the University of Edinburgh, UK, have now demonstrated that this medicine can be made from a much more unexpected source: plastic waste.
Through genetic engineering and sustainable chemical approaches, they successfully converted PET plastic (polyethylene terephthalate), commonly found in water bottles and food packaging, into paracetamol using the bacterium Escherichia coli (E. coli).
The process takes place at room temperature, produces no significant carbon emissions, and requires less than 24 hours, achieving a conversion efficiency of up to 92%.
This research was published in the scientific journal Nature Chemistry in June 2024 and funded by the EPSRC CASE Award as well as biotechnology company AstraZeneca, with support from Edinburgh Innovations.
The Process: From Plastic to Medicine
The first step involves recycling PET plastic into an initial chemical compound using environmentally friendly chemical methods. This compound is then introduced into genetically modified E. coli cultures.
The modification disables the E. coli’s ability to produce para-aminobenzoic acid (PABA)—a vital compound for its growth. Unable to synthesize PABA on its own, the bacteria are “forced” to take it from the recycled plastic-derived compound supplied to them.
Interestingly, during the transformation of the plastic-derived compound into PABA, a chemical reaction called the Lossen rearrangement occurs. This reaction typically requires extreme laboratory conditions that are inhospitable to living organisms.
However, the researchers discovered that this reaction can spontaneously occur inside living E. coli cells, aided by natural phosphate present within the cells. This marks the first time this chemical reaction has been successfully carried out in an active biological system.
From PABA to Paracetamol: The Role of Additional Genes
After producing PABA, the research team proceeded to the next stage: converting PABA into paracetamol. How? By inserting two new genes into the E. coli, each originating from fungi and soil bacteria.
These additional genes produce enzymes that enable E. coli to efficiently convert PABA into paracetamol. The results are impressive—92% of the plastic-based compound was converted into paracetamol in less than a day, without the need for high temperatures or extreme pressure.
Small and Efficient: An Energy-Friendly Process
One of the key advantages of this method is its simplicity. The conversion process can be carried out in small laboratories, requires no large industrial machinery, and operates at room temperature. In other words: it’s fast, energy-efficient, and nearly carbon-neutral.
Stephen Wallace, a biotechnologist at the University of Edinburgh who led the research, stated that this discovery proves plastic doesn’t always have to end up as useless waste.
“This work demonstrates that PET plastic isn’t just waste or a material destined to become more plastic. It can be transformed by microorganisms into valuable new products, including those with potential for treating disease,” he said in a statement.
Industrial Challenge: Still a Work in Progress
Despite the promising results, challenges remain. The process of breaking down PET plastic into its initial compounds still needs to be streamlined for industrial-scale application. Scientists note that the plastic degradation method used in the study is not yet efficient enough for mass production.
Nonetheless, the discovery is considered a crucial first step. Some experts call it a milestone toward a plastic upcycling system that not only reduces waste but also generates high-value pharmaceutical products.
The long-term vision of the research team is to engineer microorganisms capable of performing the entire process—from breaking down plastic and converting it into intermediates to producing finished medicines. If successful, this could mark a revolution in biotechnology and pharmaceuticals.
