Microbes in Cow Stomachs May Help Our Plastic Problem

Interestingly, cow stomach enzymes can break down some common plastics.
Derya Ozdemir

A set of enzymes in the stomach fluid of cows can break down some types of plastic, including the polyethylene terephthalate (PET) used in soda bottles, food packaging, and synthetic textiles, according to a new study published in the journal Frontiers in Bioengineering and Biotechnology.

Plastic is notoriously difficult to break down and causes tremendous environmental damage in the process, but science has started exploring how naturally occurring microorganisms may lend a helping hand.

In this most recent study, Georg Guebitz of the University of Natural Resources and Life Sciences in Austria and his colleagues visited a local slaughterhouse and obtained fluid samples from the rumen (the biggest compartment of a ruminant's stomach), according to a press release.

The research's starting point was when scientists suspected that microbes lurking in a cow's rumen could digest polyesters since a cow's diet already contains natural plant polyesters. So, the cows' stomachs had to have a system capable of conducting polyester hydrolysis, a chemical reaction that breaks down such compounds. Could they, however, do the same with artificial polyesters?

Once the rumen fluid was collected, the researchers incubated it with PET plastic, and also tested its performance against a biodegradable plastic called PBAT and a bioplastic called PEF. All of the polymers were tested both in powder and film form.

The team found the microbes in the rumen fluid were able to break down all three plastic types. The powders broke down faster than the films, according to the results published. The same researchers had previously looked at how single microbes could break down plastic but discovered that the rumen liquid was far more efficient. This could be due to the microbial community's synergy and the variety of enzymes they create, which is more efficient than depending on a single enzyme, researchers say.

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The technique is described as "under-explored" and it's only been demonstrated in the lab so far, so the researchers will be conducting further research. Perhaps in the future, the approach could be scaled up and the enzymes could be used to help with our plastic problem on a larger scale, possibly for much cheaper than the current technologies.

In recent years, there've been a number of promising studies showing how bacteria could help eat away at our plastic pollution problem. Scientists were able to convert plastic bottles into vanillin using bacteria, for example. We also know that there are mushrooms that eat plastic: Some mushroom species have the ability to consume polyurethane, which is one of the main ingredients in plastic products.

The research on these novel techniques is currently expensive, and speed can be a problem, too, when breaking down plastics. Still, the team will continue researching the topic, and time will show the potential this technique holds.  

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