Scientists Develop Plastic-Eating E. coli to Convert PET Bottles into Adipic Acid

In a groundbreaking development, researchers at the University of Edinburgh have engineered a strain of E. coli that efficiently converts polyethylene terephthalate (PET) waste from plastic bottles into adipic acid. Adipic acid is a versatile feedstock used in the production of nylon materials, drugs, and fragrances.

Mountains of used plastic bottles get thrown away every day, but microbes could potentially tackle this problem. Now, researchers in ACS Central Science report that they’ve developed a plastic-eating E. coli that can efficiently turn polyethylene terephthalate (PET) waste into adipic acid, which is used to make nylon materials, drugs, and fragrances.

Previously, a team led by Stephen Wallace had modified E. coli to transform terephthalic acid, the primary component of old PET bottles, into vanillin, the compound responsible for the vanilla flavor. Building on this, the new research aimed to expand E. coli's biosynthetic pathways to include the conversion of terephthalic acid into adipic acid, a substance usually derived from fossil fuels through energy-intensive processes.

The researchers engineered a new strain of E. coli to produce enzymes capable of transforming terephthalic acid into compounds like muconic acid and adipic acid. To convert muconic acid into adipic acid, they employed a second type of E. coli producing hydrogen gas and a palladium catalyst. The team found that attaching the modified microbial cells to alginate hydrogel beads significantly enhanced efficiency, with up to 79% conversion of terephthalic acid into adipic acid in experiments.

Using real-world samples from a discarded bottle and waste packaging labels, the engineered E. coli system proved effective in producing adipic acid. Moving forward, the researchers plan to explore pathways for biosynthesizing additional higher-value products. The study received funding from the Carnegie Trust for the Universities of Scotland, the Industrial Biotechnology Innovation Centre, UK Research and Innovation, and the Engineering and Physical Sciences Research Council Sustainable Manufacturing grant.