Renewable Plastic from Glucose-Fed Microbes
Polyhydroxyalkanoates (PHA) are a class of polyesters naturally produced by bacteria. PHA has structural properties that make it attractive as a renewable plastic. Especially promising is medium chain-length PHA (mcl-PHA), which consists of fatty acids containing six or more carbons. This form of PHA could be useful in medical devices, cosmetics and tissue engineering.
Most naturally produced PHA contains random monomeric sequences undesirable for commercial use. Fortunately, its structure can be tweaked by feeding monomers and precursors (e.g., fatty acids) to a microbe. PHA with varying degrees of crystallinity and elasticity has been engineered in this way.
Low-cost sources of such lipid monomers and precursors are not available. For this reason, current PHA research is focused on engineering metabolic pathways able to convert less expensive, more renewable sources like glucose.Description
UW–Madison researchers have developed recombinant E. coli capable of producing high yields of mcl-PHA from non-lipid, carbohydrate sources. The researchers previously designed and built a bacterial strain that produces high levels of C12 fatty acids (see WARF reference number P09329US02). This strain has been further modified by deleting various fad genes implicated in the breakdown of fatty acids. Also, the bacteria cells incorporate several genes taken from other species to increase conversion efficiency.Benefits
- Yields of mcl-PHA homopolymers are the highest known.
- Glucose is inexpensive and abundant.
- E. coli is a hardy microbe easily utilized in biomanufacturing.
Making renewable PHA for use in packaging, pharmaceuticals and other plastic productsMore Information
For More Information About the Inventors: Brian Pfleger
Publications: Lennen R.M., Braden D.J., West R.A., Dumesic J.A. and Pfleger B.F. 2010. A Process for Microbial Hydrocarbon Synthesis: Overproduction of Fatty Acids in Escherichia coli and Catalytic Conversion to Alkanes. Biotechnol. Bioeng. 106, 193-202.Technology Status
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