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Microbiology: E. coli used to produce renewable plastics
E. coli bacteria could be used to create biodegradable plastics, reports a paper published in Nature Chemical Biology. The engineered bacterial system described in the study may help in the production of plastics with desirable thermal and mechanical properties, using renewable resources, the authors suggest.
Global plastic production was estimated to have created about 400 million metric tons of plastic in 2022, mostly through petroleum-based chemical processes. Meanwhile, the microbial production of polymers has the potential to develop biodegradable alternatives in a more sustainable way. It is well known that organisms can naturally synthesise polymers, such as DNA, RNA, cellulose and proteins. However, scientists have only recently focused on the use of microorganisms to synthesize polymers that can be used to manufacture plastics.
Sang Yup Lee and colleagues developed a process to produce poly(ester amide) (PEA) using a series of enzymes, produced in E. coli; this process involves combining one or more of six amino acids with one or more hydroxy acids to create the polymer plastic. After further tests to optimise the process, Lee and colleagues used glucose as a key ingredient to produce the polymers within E. coli. They also investigated how the amount and structure of the different amino acids used affects the production and properties of the PEAs. As a proof of concept, the authors produced about 55 grams per liter of a PEA in a large bioreactor, demonstrating that PEA production can be easily scaled up. They also tested the physical, thermal and mechanical properties of this PEA, and suggest that they are comparable to those of high-density polyethylene, one of the most widely used plastics, which indicates that PEAs could serve as a renewable alternative.
This method has several advantages over current chemical methods, such as providing easy access to a wide range of PEAs and enabling the sustainable production of polymers that could be used as plastics, the authors conclude.
