Researchers have made significant strides in creating a microbial strain capable of producing a pseudoaromatic polyester monomer, which can serve as an alternative to polyethylene terephthalate (PET), through systems metabolic engineering.
Today, plastic waste poses major environmental challenges globally. The KAIST research team has pioneered a biodegradable, microbial-based plastic that could potentially replace traditional PET bottles, drawing substantial attention.
On November 7th, the university announced that a research team led by Distinguished Professor Sang Yup Lee from the Department of Chemical and Biomolecular Engineering has successfully engineered a microbial strain that can produce pseudoaromatic polyester monomers efficiently, aiming to replace PET.
Pseudoaromatic dicarboxylic acids, when transformed into polymers, boast superior physical characteristics and higher biodegradability compared to conventional PET. These compounds are emerging as eco-friendly alternatives for polymer synthesis. However, traditional chemical methods for producing these acids often yield low quantities and selectivity, require complex reaction conditions, and can generate toxic waste.
To address these issues, Professor Sang Yup Lee’s team applied metabolic engineering to create a microbial strain that effectively generates five varieties of pseudoaromatic dicarboxylic acids, which include 2-pyrone-4,6-dicarboxylic acid and four types of pyridine dicarboxylic acids (2,3-, 2,4-, 2,5-, and 2,6-pyridine dicarboxylic acids). This was achieved using Corynebacterium, a bacterium often utilized in amino acid production.
The research group enhanced the microbial platform by optimizing the metabolic flow of protocatechuic acid, a precursor for several pseudoaromatic dicarboxylic acids, while preventing precursor loss.
Through transcriptome analysis, the team identified genetic targets, enabling the production of 76.17 g/L of 2-pyrone-4,6-dicarboxylic acid. Additionally, they successfully developed three metabolic pathways for producing pyridine dicarboxylic acids, resulting in yields of 2.79 g/L for 2,3-pyridine dicarboxylic acid, 0.49 g/L for 2,4-pyridine dicarboxylic acid, and 1.42 g/L for 2,5-pyridine dicarboxylic acid.
The research team also achieved a remarkable production of 15.01 g/L of 2,6-pyridine dicarboxylic acid by improving the corresponding biosynthesis pathway, culminating in the high-efficiency creation of five similar aromatic dicarboxylic acids.
In summary, the researchers have successfully produced 2,4-, 2,5-, and 2,6-pyridine dicarboxylic acids at unprecedented concentrations globally. Notably, the production of 2,4- and 2,5-pyridine dicarboxylic acids reached gram-per-liter scales, a significant increase from their previous low yields.
This research is anticipated to be applied across various industrial polyester production processes and is expected to further stimulate advancements in producing analogous aromatic polyesters.
Professor Sang Yup Lee, the principal investigator, emphasized, “The importance of our work lies in establishing an eco-friendly method that enables efficient production of similar aromatic polyester monomers through microbial processes.” He added, “This research will facilitate a transition toward a microorganism-based bio-monomer industry, potentially supplanting the petrochemical sector in the future.”
The findings of this research were published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS) on October 30th.
This study received support from the Development of Next-generation Biorefinery Platform Technologies for the Leading Bio-based Chemicals Industry Project and the Development of Platform Technologies of Microbial Cell Factories for the Next-generation Biorefineries Project, both funded by the National Research Foundation of Korea under the Ministry of Science and Technology and ICT.
