Endlessly recyclable plastic made by bacteria

Researchers at Berkeley Lab, US, developed a way to engineer bacteria to produce raw materials that can be turned into plastic, and are endlessly recyclable.

The majority of the plastic products available are made of fossil fuels, which do not break down. Of all those products, only a fraction is recycled and usually even downcycled (i.e. a product of a lesser quality than the previous product). The rest end up on the landfill, or worse, the waterways and oceans.

In 2019, Berkley Lab developed a new type of plastic called polydiketoenamine (PDK), in which the bonds between molecules can more easily be broken on demand so it can be recycled without loss of quality. In those previous studies, the researchers used the same petrochemicals that go into regular plastic.

In the new study, however, they turned to a renewable resource. The ream engineered the bacterium E. coli in such a way that it could convert sugars from plants into a molecule called triacetic acid lactone (TAL). This can be combined with other chemicals to produce PDK.

The result is a plastic material that can be selectively tuned to be flexible, tough or even adhesive, depending on the application. Not only is the material more sustainable than the previous versions, it also can handle hotter working temperatures, up to 60 °C (140 °F), for more applications.

Currently, the new PDK contains about 80% bio-content, but the team aims for 100% in the future.

Image: Jeremy Demarteau/Berkeley Lab