Scientists globally are developing microbes that can produce plastics as an alternative to the traditional petroleum-based industry. Recent advancements from researchers in Korea have successfully addressed a significant challenge: enabling bacteria to create polymers that feature ring-like structures, which enhance the rigidity and thermal stability of plastics. Typically, these molecules are harmful to microorganisms, so the team needed to design a unique metabolic pathway for E. coli to produce and manage the buildup of both the polymer and its building components. The polymer developed is biodegradable and possesses characteristics that may be beneficial for biomedical uses, such as in drug delivery, although further study is required. These findings were published on August 21 in the journal Trends in Biotechnology.
Senior author Sang Yup Lee, a chemical and biomolecular engineer at the Korea Advanced Institute of Science and Technology, states, “I believe biomanufacturing is crucial for addressing climate change and the global plastic issue. We need international collaboration to enhance bio-based manufacturing, ensuring a healthier environment for future generations.”
Most conventional plastics employed in packaging and industries feature ring-like “aromatic” structures, like PET and polystyrene. While earlier research has succeeded in creating microbes that generate polymers consisting of alternating aromatic and aliphatic (non-ring) monomers, this represents the first instance where microbes have produced polymers exclusively from monomers with aromatic sidechains.
The researchers achieved this by initially creating a new metabolic pathway through the recombination of enzymes from various microorganisms, enabling the bacteria to synthesize an aromatic monomer known as phenyllactate. Subsequently, they utilized computer simulations to design an efficient polymerase enzyme that could link these phenyllactate units into a polymer.
“This enzyme replicates the polymer more effectively than any natural enzymes,” Lee notes.
After refining the bacteria’s metabolic pathway and optimizing the polymerase, the team cultivated the microbes in fermentation vats with a capacity of 6.6 liters (1.7 gallons). The resulting microbial strain was able to produce 12.3 g/L of the polymer (poly(D phenyllactate)). The goal is to enhance the yield to at least 100 g/L for commercialization.
According to Lee, “Given its characteristics, we believe this polymer could be particularly suitable for drug delivery. Though it isn’t as strong as PET, primarily due to its lower molecular weight.”
Looking ahead, the researchers aim to develop new types of aromatic monomers and polymers with diverse chemical and physical traits, such as higher molecular weights necessary for industrial applications. Additionally, they are focused on further optimizing their methods for scalability.
Lee emphasizes, “By increasing the yield, this technique could potentially be commercialized on a larger scale. We are enhancing both our production and purification processes to economically isolate the polymers we create.”
This research received funding from the National Research Foundation and the Korean Ministry of Science and ICT.
