Researchers engineer bacteria to produce plastics

Most of the polymers incorporated a fair amount of lactic acid, which can also form ester bonds. There’s normally lots of lactic acid in the cell since it’s one of the potential products of glucose metabolism. But the researchers knocked out the gene that encodes the primary enzyme that produces with lactic acid, dramatically cutting down the amount incorporated into the polymer.

The researchers also tried a variety of conditions, showing that they could create polymers that were a mixture of two different amino acid monomers, and incorporating non-amino acids into the mixture. By adding a few additional enzymes to the E. coli strain, they managed to boost the yield of the polymer by weight to over 50 percent. They also showed that you could introduce mutations to the enzyme that does the polymerization, and it would selectively incorporate more of a specific amino acid into the resulting polymer.

Overall, the system they develop is remarkably flexible, able to incorporate a huge range of chemicals into a polymer. This should allow them to tune the resulting plastic across a wide range of properties. And, considering the bonds were formed via enzyme, the resulting polymer will almost certainly be biodegradable.

There are, however, some negatives. The process doesn’t allow complete control over what gets incorporated into the polymer. You can bias it toward a specific mix of amino acids or other chemicals, but you can’t entirely stop the enzyme from incorporating random chemicals from the cell’s metabolism into the polymer at some level. There’s also the issue of purifying the polymer from all the rest of the cell components before incorporating it into manufacturing. Production is also relatively slow compared to large-scale industrial production.

So, it’s not quite ready to take over global plastic production. But the work does do a great job of highlighting the potential of bio-based manufacturing.

Nature Chemical Biology, 2025. DOI: 10.1038/s41589-025-01842-2  (About DOIs).