In a remarkable twist on plastic pollution and pharmaceutical production, scientists have engineered a harmless bacterium (Escherichia coli) to transform used plastic into paracetamol.

It’s one of the world’s most common bacteria creating one of the world’s most commonly used painkillers, and the same technique could be used to produce a trove of different drugs, the researchers say. It has an added bonus, too: it can reduce our reliance on fossil fuels.

From trash to treatment

Today, paracetamol is made from fossil fuels in energy-intensive factories, contributing significantly to greenhouse gas emissions. The world consumes a lot of paracetamol, around 275 thousand tonnes of it. This creates somewhere over 1 million metric tons of CO₂ per year. Plus, there’s all the plastic packaging that’s needed for the medicine. The researchers argue that their method offers a cleaner, more sustainable alternative.

The process runs at room temperature, produces virtually no carbon emissions, and repurposes one of the world’s most problematic pollutants.

The heart of the discovery lies in a chemical sleight of hand called the Lossen rearrangement. This is an old reaction, first discovered in 1872, that turns certain molecules into primary amines, the chemical building blocks found in many pharmaceuticals. The key, however, is that this reaction had never been used inside a living organism.

The Edinburgh team figured out how to pull it off using phosphate, a common cellular chemical, as a catalyst. They reprogrammed E. coli to convert terephthalic acid — a compound that comes from breaking down polyethylene terephthalate (PET), the plastic used in water bottles — into para-aminobenzoic acid (PABA). Next, they dug even deeper into their bag of tricks, borrowing a couple of enzymes from a mushroom and a bacterium. They then edited a few genes and, only then, the microbes finished the job and produced paracetamol.

This produces virtually zero emissions and can be done in less than 24 hours, the researchers say. In fact, the whole process is comparable to the fermentation in brewing beer. According to the researchers behind this study, this hybrid approach — melding traditional chemistry with microbial metabolism — could eventually be used to make not just paracetamol, but a whole range of sustainable chemicals.

Turning plastic into something useful

While the lab-scale experiments are promising, this isn’t ready to replace traditional pharmaceutical manufacturing — yet.

This approach won’t change how we produce paracetamol overnight, and it won’t dent plastic pollution anytime soon, either. But it adds to a growing stack of methods that can help us turn plastic pollution into something useful.

Globally, more than 350 million tons of plastic waste are produced each year. PET, commonly used in packaging, makes up a significant chunk of that. While it is technically recyclable, most recycling processes either downcycle it into lower-quality plastic or involve significant emissions. The new study shows that plastic can instead be upcycled into something as valuable as a medication.

“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,” says Professor Stephen Wallace UKRI Future Leaders Fellow and Chair of Chemical Biotechnology.

This research is a vivid example of how seemingly unrelated fields — plastic recycling, pharmaceutical manufacturing, and microbial metabolism — can come together to solve some of the planet’s toughest challenges.

A plastic bottle might seem like the end of a product’s life. But in the right hands — and the right bacteria — it could be just the beginning.

The study was published in Nature Chemistry.