Researchers have discovered that bacteria living inside a cow’s gut can break down several types of plastic
If William Shakespeare had used biros to write his plays, we’d still be unearthing the bard’s spent pens today – plastic is a notoriously hard material to break down.
However, researchers in Austria have made a discovery that could help deal with some of the millions of tonnes of single-use plastic that the world throws away annually.
Scientists at the University of Natural Resources and Life Sciences in Vienna found that bacteria living inside a cow’s rumen – one of the four compartments of its stomach – can digest certain plastics, including those used to make single-use packaging. The next step is to identify the microbes responsible, so they can be engineered in labs.
The researchers suspected that rumen liquid could be useful in breaking down plastics, because a cow’s diet typically contains natural plant polyesters.
So they obtained some from an abattoir, and incubated it with the three types of plastics: polyethylene terephthalate (PET), used to make drinks bottles; polybutylene adipate terephthalate (PBAT), typically found in compostable bags; and polyethylene furanoate (PEF), another biodegradable plastic used in compatible bags.
The results of the study, published in Frontiers in Bioengineering and Biotechnology, found that all three plastics could be broken down in “hours” by the rumen liquid.
Plastic takes hundreds of years to break down, posing a problem to wildlife. Image: Brian Yurasits
“Due to the large amount of rumen that accumulates every day in slaughterhouses, upscaling would be easy to imagine,” said Dr Doris Ribitsch, who led the research.
However, the more ethical and sustainable next step is to identify the microbes responsible for breaking down plastic from the thousands present in the rumen liquid. These could then be cultivated in labs, rather than being sourced from abattoirs.
As plastic pollution becomes more pervasive and problematic, the race is on to develop enzymes that can eat the stuff. At the vanguard of such research is the University of Portsmouth in England, and the National Renewable Energy Laboratory in the US. In September, their trans-Atlantic team of scientists engineered a ‘super-enzyme’ that is capable of breaking PET plastic down into its building blocks in a matter of hours.
The discovery was described by scientists at the University of Portsmouth as “another leap towards beating plastic waste”.
Calls for global treaty to end ‘virgin’ plastic production
Scientists are calling for a global treaty to phase out the production of virgin plastics by 2040. In a special report in the journal Science, researchers have made the case for limits and controls.
“Plastics are increasingly found in all environmental media, including terrestrial ecosystems and the atmosphere, as well as human matrices, including lungs and placenta,” wrote the authors.
“We therefore argue for a new international legally binding agreement that addresses the entire life cycle of plastics, from extraction of raw materials to legacy plastic pollution. Only by taking this approach can efforts match the magnitude and transboundary nature of this escalating problem and its social, environmental, and economic impacts.”
Main image: Jakob Cotton
