May 19, 2025 – The global menace of traditional plastic pollution has intensified the urgency for sustainable alternatives, with polyhydroxyalkanoates (PHA)—biodegradable polymers—emerging as a promising solution. However, their high production costs have hindered large-scale adoption. In a breakthrough approach, researchers are now exploring waste plastics as carbon sources for microbial PHA synthesis, addressing both plastic recycling challenges and cost barriers. Among these, terephthalic acid (TPA), a hydrolysis product of polyethylene terephthalate (PET), shows significant potential, though efficient microbial conversion remains a key technical hurdle.
A research team led by Dr. Wang Yin from the Institute of Urban Environment, Chinese Academy of Sciences, has made innovative strides in this field. Through shake flask experiments, the team enriched mixed microbial communities from sludge and utilized TPA derived from PET hydrolysis as a carbon source in a 5-liter bioreactor via fed-batch fermentation, successfully converting TPA into PHA. Experimental data revealed a maximum PHA concentration of 2.25 g/L and a conversion rate of 0.10 gPHA/gTPA. Using gene annotation and intermediate metabolite identification, the researchers systematically uncovered the composition of dominant microbial communities and the metabolic pathways of TPA conversion. Results showed that mixed 菌群 (microbial consortia) achieved synergistic degradation, with distinct bacterial species secreting specific enzymes to gradually transform TPA into protocatechuic acid or catechol, ultimately generating acetyl-CoA—the precursor for PHA biosynthesis.
This study not only provides a sustainable pathway to upcycle waste PET into biodegradable polymers but also elucidates the metabolic mechanisms crucial for enhancing PHA production yields in future research. Published in the authoritative environmental journal Chemical Engineering Journal under the title “Metabolic mechanism in biosynthesis of polyhydroxyalkanoate from terephthalic acid by mixed microbial consortium,” the research was co-led by Dr. Pan Lanjia (Special Research Assistant) and master’s student Wardah Hayat Khan, with Dr. Li Jie (Special Research Assistant) and Dr. Wang Yin serving as corresponding authors. The project was funded by multiple grants, including the Chinese Academy of Sciences Special Research Assistant Program, Xiamen Overseas Scholars Research Project, and Fujian Provincial Key Science and Technology Program.
By bridging plastic waste valorization with biodegradable material production, this work paves the way for a circular economy model in the plastics industry, offering both environmental and economic benefits. As microbial engineering technologies advance, the scalable production of PHA from waste plastics could revolutionize sustainable materials science.