Piles of used plastic bottles are thrown away every dayBut microorganisms may be able to solve the problem. Now, researchers at ACS Central Science report that they have developed a plastic-eating E. coli strain that efficiently converts polyethylene terephthalate (PET) waste into adipic acid for use in Manufacture of nylon materials, pharmaceuticals and perfumes.
Previously, a team of researchers, including Stephen Wallace, engineered a strain of E. coli to convert terephthalic acid, the main ingredient in old PET bottles, into something tastier and more valuable: the vanilla-flavored compound aroma Lansu. Meanwhile, other researchers engineered microorganisms to metabolize terephthalic acid into a variety of small molecules, including short acids. So Wallace and a new team at the University of Edinburgh wanted to expand E. coli's biosynthetic pathway to include metabolism of terephthalic acid into adipic acid, a raw material for many everyday products, often from energy-intensive processes. Produced from fossil fuels.
The team developed a new strain of E. coli that produces enzymes that convert terephthalic acid into compounds such as myxic acid and adipic acid. Then, to convert mucinic acid into adipic acid, they used a second hydrogen-producing E. coli and a palladium catalyst. In experiments, the team found that attaching engineered microbial cells to alginate hydrogel beads increased their efficiency, with up to 79% of terephthalic acid being converted into adipic acid. Using samples of terephthalic acid extracted from discarded bottles and coatings extracted from discarded packaging labels, the engineered E. coli system efficiently produced adipic acid. The researchers said that in the future they will look for ways to biosynthesize other high-value products.
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