Global plastic pollution is becoming increasingly serious, with aromatic plastics derived from petroleum being a major concern due to their difficulty in decomposition. In an effort to address this issue, scientists in South Korea have successfully genetically modified bacteria to produce degradable aromatic polyesters, which could potentially replace some petroleum-based plastics in manufacturing.
The excellent processing performance, durability, and relatively low cost of plastics have made them an essential part of everyday life and industry. However, the majority of plastics are derived from ethylene, propylene, and other alkanes distilled from petroleum, which are then processed chemically to create aromatic plastics.
The production process of plastics can cause environmental damage and pollution, and plastics are often resistant to microbial degradation. Scientists aim to produce “aromatic polyhydroxyalkanoates (PHA),” peptides (such as spider silk), cellulose, and other polymers through microbial production, as alternatives to petroleum-based plastics, yet these alternatives still cannot fully meet the demands of the contemporary plastic market.
PHA is a type of polymer synthesized in various microorganisms that is biodegradable. Recently, researchers at the Korea Advanced Institute of Science and Technology (KAIST) transformed Escherichia coli into a microorganism capable of producing aromatic polyesters using synthetic biology metabolic engineering techniques. They then used this to manufacture degradable plastics, aiming to replace petroleum plastics.
This marks the first time microorganisms have been able to produce a monomer polymer with fully aromatic side chains. The research findings were published in “Biotechnology Trends” by Cell Press on August 21, with support from the National Research Foundation of Korea, the Ministry of Science and ICT of Korea.
Researchers designed a PHA synthetic enzyme and inserted it into E. coli strains, enabling the bacteria to synthesize aromatic polyesters when fed with glucose and succinic acid. Subsequently, the research team screened the modified E. coli strains through multiple selections, observing their production to identify the optimal strain.
Using the genetically modified E. coli, the research team achieved the highest recorded production yield of aromatic polyesters to date.
The team also verified the industrial potential of this technology and the purity of the polymers it produces.
The researchers mentioned that the products produced currently could potentially be used in automotive components, PBT (thermoplastic engineering polymer), and other related consumer goods. While showcasing potential for commercial-scale production, further optimization is needed to meet ideal production levels for commercialization.
Furthermore, they plan to develop other types of aromatic monomers and polymers to attain various chemical and physical properties for industrial applications, expanding production scale to contribute significantly to the future of plastic recycling and sustainable production.
Lead author and chemical and biochemical engineer at KAIST, Sang Yup Lee, expressed that biologically produced plastics will play a vital role in alleviating the global plastic crisis. He emphasized the need for international collaboration to advance bio-based manufacturing for a better environment in the future.
Lee stated that the enzyme they developed can synthesize polymers more effectively than any enzyme currently available in nature. Although the strength of the polymer is lower than polyethylene terephthalate (PET) due to its lower molecular weight, this feature could make it particularly suitable for drug delivery applications.
He also mentioned that by increasing production yields, the method could potentially be scaled up for commercialization. Efforts are underway to enhance efficiency in both production and recycling processes to economically purify the polymers they produce.