South Korean scientists from KAIST University and LG Chem have engineered a strain of E. coli to produce polylactic acid (PLA) and its copolymers through direct fermentation. Until now PLA has been produced in a two-step fermentation and chemical process of polymerization, which is both complex and expensive.
The research will be published in two papers in the journal Biotechnology and Bioengineering.
The polyesters and other polymers we use everyday are mostly derived from fossil oils made through the refinery or chemical process. The idea of producing polymers from renewable biomass has attracted much attention due to the increasing concerns of environmental problems and the limited nature of fossil resources. PLA is considered a good alternative to petroleum-based plastics as it is both biodegradable and has a low toxicity to humans.—Professor Sang Yup Lee , KAIST University
The one-stage process through direct fermentation makes the renewable production of PLA and lactate-containing copolymers cheaper and more commercially viable.
By developing a strategy which combines metabolic engineering and enzyme engineering, we’ve developed an efficient bio-based one-step production process for PLA and its copolymers. This means that a developed E. coli strain is now capable of efficiently producing unnatural polymers, through a one-step fermentation process.—Professor Lee
This combined approach of systems-level metabolic engineering and enzyme engineering now allows for the production of polymer- and polyester-based products through direct microbial fermentation of renewable resources.
Global warming and other environmental problems are urging us to develop sustainable processes based on renewable resources,” concluded Lee. “This new strategy should be generally useful for developing other engineered organisms capable of producing various unnatural polymers by direct fermentation from renewable resources.—Prof. Lee
Taek Ho Yang, Tae Wan Kim, Hye Ok Kang, Sang-Hyun Lee, Eun Jeong Lee, Sung-Chul Lim, Sun Ok Oh, Ae-Jin Song, Si Jae Park, Sang Yup Lee (2009) Biosynthesis of Polylactic acid and its Copolymers Using Evolved Propionate CoA Transferase and PHA Synthase. doi: 10.1002/bit.22547
Yu Kyung Jung, Tae Yong Kim, Si Jae Park, Sang Yup Lee (2009) Metabolic Engineering of Escherichia coli for the Production of Polylactic Acid and its Copolymers. doi: 10.1002/bit.22548