Aromatic polyesters are sought after for the manufacture of strong plastics with stability in heat. Normally produced from petroleum, these compounds have yet to be reliably produced from renewable biomass sources. Recently, a research team from KAIST University in South Korea engineered E. coli to produce aromatic polyesters from feedstock carbohydrates in a one-step fermentative process.
"An eco-friendly and sustainable chemical industry is the key global agenda every nation faces. We are making a research focus to a biochemical industry free from petroleum dependence, and conducting diverse research activities to address the issue,” said principal researcher Sang Yup Lee. “This novel technology we are presenting will serve as an opportunity to advance the biochemical industry moving forward."
According to their recent publication in Nature Communications, the team first identified key CoA-transferase enzymes that can efficiently activate phenylalkanoates into aromatic polyester precursors. Cells were then metabolically engineered to produce phenylalkanoates from glucose. The team found that overexpressing the enzymes PHA synthase and hydroxyisocaproate CoA-transferase (HadA) resulted in polymerization of the aromatic polyesters. Further strain engineering finally yielded cells that can produce the polyesters directly from glucose.
To produce different aromatic polyesters with varying compositions, enzyme expression levels were further modulated. Various aromatic acyl-CoA precursors were indeed produced and confirmed with in-vitro assays and liquid chromatography-mass spectrometry.
The team’s paper concludes that “the engineered bacterial system will be useful for one-step fermentative production of aromatic polyesters from renewable resources.” This new environmentally friendly biosynthetic system also proves the potential of expanding the range of aromatic polyesters, which is expected to play an important role in the bio-plastic industry.
Image: Overall conceptualization of how metabolically engineered E. coli produced aromatic polyesters from glucose. Image courtesy of KAIST.