Plastic-Eating Bacteria Turn Waste Into Useful Materials

Scientists have created a special plastic-eating bacteria, E.coli, that can feed on plastic bottles made of polyethylene terephthalate (PET) and convert them into adipic acid. This acid is useful in making nylon substances, medicines, and fragrant materials in general.

In a report published in ACS Central Science, the process by which E. coli can break down regular plastic bottles and other plastic waste is revealed.

Recycling of plastic for useful materials

Each day, the equivalent of two thousand garbage truck loads full of trash is discarded into our oceans and rivers. In order to help the planet by recycling, we might convert used materials into “new” substances by breaking it down and using it for something new. However, innovative methods of dealing with the overwhelming amount of garbage are needed.

Scientists at the University of Edinburgh came up with a brilliant plan. They produced a special E. coli that could change the main component of plastic bottles, called terephthalic acid, into a fancy and valuable material called vanillin, which is what gives vanilla its delicious taste.

Conversion of terephthalic acid into adipic acid

A different group of researchers from the University of Edinburgh, led by Professor Stephen Wallace, has achieved something impressive with the plastic-eating bacteria. The scientists have managed to train E. coli to turn terephthalic acid into adipic acid. Usually, adipic acid comes from fossil fuels in a very energy-hungry process.

Professor Wallace, an expert on chemicals and biology, explained, “We use a technique called synthetic biology, where we insert new pieces of DNA into E. coli that program the cell to perform new chemical reactions.”

He further said, “Here we programmed bacteria to made adipic acid from plastic waste [which] now enables nylon for clothing to be made from a waste plastic bottle.”

Process of conversion through plastic-eating bacteria

The new E. coli scientists created produces enzymes that convert terephthalic acid into shorter acids such as muconic and adipic acid. To complete this conversion, they used another kind of E. coli that makes hydrogen gas, along with a special helper called palladium.

They discovered that if they placed the special E. coli on tiny gel beads made of alginate, it worked even better. In the tests, they were able to change as much as 79 percent of the terephthalic acid into adipic acid using this new method, which is the first of its kind.

Testing plastic-eating bacteria on real samples

Once scientists confirmed this was possible, they tested it on actual objects. They used the E. coli on two real-life samples: a plastic bottle they found on the street and some plastic waste from a company in Scotland. It turns out that E. coli did a great job on both of these.

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Professor Wallace said, “We applied these strains to both a plastic bottle we found on the street and a sample of plastic waste generated by a local industrial company in Scotland, and they both worked remarkably well.”

“This demonstrates to us how plastic waste can serve as a new feedstock for chemical production and we’re currently applying this finding to a range of different industrial products,” said Wallace.

Eco-friendly ways to recycle plastic

The scientists confirm in their report that coming up with eco-friendly ways to recycle plastic is a smart move for the lifecycle of chemicals. The new method is efficient because it works at room temperature, with normal pH, and it is all done within the span of a single day, which means it can be used more widely.

“We are currently working intensely with a number of industrial partners in the UK and beyond to intensify this process so that we can make real-world clothing fibers from plastic waste,” Wallace noted. “This is also just the beginning of what I think we can do—so watch this space!”