Common plastics can be broken down by enzymes found in cow stomachs

By Krista Charles

Cows in the Karwendel mountains of AustriaThomas Winz/Getty Images
Cows have stomachs with four compartments and the bacteria in one of them – the rumen – produce enzymes which can break down some widely used plastics. The discovery could lead to new technology for processing such materials after use.
Georg Guebitz at the University of Natural Resources and Life Sciences in Austria and his colleagues visited a local slaughterhouse and collected samples of the liquid from the rumen of a young ox fed on alpine pastures. They found that the liquid contained many types of enzymes, including cutinases.
The team demonstrated that these enzymes could break down three types of widely used polyesters – namely polyethylene terephthalate (PET), polybutylene adipate terephthalate (PBAT) and polyethylene furanoate (PEF), which are often used to make products including bottles, textiles and bags. The enzymes degraded these substances within one to three days when kept at a temperature of about 40°C to match that of a cow’s stomach.Advertisement
“We found that the diet of cows contains foods that have a ‘shell’ that is similar to polyesters,” says Guebitz: this explains why the microbes within the rumen produce enzymes that can also deal with synthetic polyesters.

In future, these enzymes could be used to break down polyesters on a larger, commercial scale, says Guebitz. This may, at least potentially, be cheaper than the technologies currently used to process the plastics, he says – but other researchers are cautious about this.
“It has to be proven that the enzymatic activity is the same or better than what is commercially being implemented today,” says Ramani Narayan at Michigan State University. “If they were to fast-track to an engineering process, then there is a lot of work that needs to be done in terms of what is the yield of the product, what is the productivity and so on, to compare with existing enzyme technology.”
Journal reference: Frontiers in Bioengineering and Biotechnology, DOI: 10.3389/fbioe.2021.684459/full

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The Science magazine report can be read here

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Have more than one trick in your bagReuse your bags to limit their impact. Slip your reusable bags into your purse, car, gym bag so that you always have reusable bags with you. By doing this, you will contribute to a circular economy that respects the environment.Adopt your new reusable bagWicker baskets, shopping nets, tote bags, etc., many sustainable alternatives exist and are now available to everyone. Not only ecological, but use them to make a statement about your commitment to the planet.Surfrider tote bag

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