Researchers in Korea have made a groundbreaking advancement in the quest to develop eco-friendly plastics by engineering bacteria to produce polymers with ring-like structures. These structures significantly enhance the rigidity and thermal stability of the resulting plastics, offering a promising alternative to traditional petroleum-based plastics.

Senior author Sang Yup Lee emphasized the potential impact of this innovation, stating, “I think biomanufacturing will be key to mitigating climate change and addressing the global plastic crisis.”

One of the major challenges the team faced was that ring-containing molecules are typically toxic to microorganisms. To overcome this, the researchers designed a unique metabolic pathway that enables E. coli bacteria not only to synthesize the polymer but also to tolerate the accumulation of both the polymer and its precursors. The resulting polymer is biodegradable and exhibits physical properties that could be particularly valuable in biomedical applications, such as drug delivery systems.

First-Ever Microbial Production of Aromatic and Aliphatic Polymers

Most plastics used in packaging and industrial applications, like PET and polystyrene, contain aromatic, ring-like structures. To replicate these properties, the researchers created a novel metabolic pathway by integrating enzymes from various microorganisms. This innovation enabled the bacteria to produce an aromatic monomer called phenyllactate. Using computer simulations, they then designed a polymerase enzyme capable of efficiently assembling these phenyllactate monomers into a fully aromatic polymer.

“This enzyme can synthesize the polymer more efficiently than any of the enzymes available in nature,” Lee noted.

Scaling Up for Industrial Use

After optimizing the bacteria’s metabolic pathway and the polymerase enzyme, the researchers scaled up their experiments by cultivating the engineered microbes in 6.6-liter (1.7-gallon) fermentation vats. The optimized strain successfully produced 12.3 grams per liter of the polymer, poly(D-phenyllactate). However, to make this method viable for commercial use, the team aims to increase this yield to at least 100 grams per liter.

The researchers are also focused on further optimizing their process to enable larger-scale production. “If we put more effort into increasing the yield, then this method might be able to be commercialized at a larger scale,” said Lee. “We’re working to improve the efficiency of our production process as well as the recovery process, so that we can economically purify the polymers we produce.”

This breakthrough could pave the way for a more sustainable future in plastics manufacturing, offering a viable alternative to the current petroleum-based industry while addressing the environmental challenges posed by plastic waste.

By Impact Lab