German study casts doubt on 'plastic digesting' caterpillars

September 15, 2017
A handout picture released by the Spanish National Research Council (CSIC) shows a moth caterpillar on a plastic bag during a scientific experiment in Santander on April 17, 2017

Scientists in Germany on Friday cast doubt on the work of colleagues who claimed that plastic bag-eating caterpillars might hold the answer to the planet's growing synthetic waste problem.

That study, led by Federica Bertocchini of the University of Santander in Spain, concluded that larvae of the wax moth, Galleria mellonella, break down polyethylene as it passes through their digestive system.

Polyethylene, ubiquitous in plastic bags and packaging, poses a major threat to the environment, including for animals that get entangled in it, if not properly recycled.

Bertocchini and her team reported study results in April claiming to show that wax moth caterpillar intestines chemically biodegrade plastic.

But rival researchers from the Johannes Gutenberg University in Mainz, Germany, said the original work did not show "sufficient proof for the bio-degradation of polyethylene".

It remains unclear, they said in a statement, whether the caterpillars digest the plastic with enzymes in their gut, or whether they break the substance down through a process of "mechanical milling"—in which case the plastic would be excreted chemically unchanged.

The Bertocchini team had applied a mush of squished wax moth caterpillars to plastic in the lab, and reported it breaking down into ethylene glycol.

From this they concluded that an enzyme may be at work, which might inspire a plastic-dissolving substance that could be produced in large quantities to eradicate ever-growing plastic mountains.

But the German team said that "essential signals of ethylene glycol are missing" from the original study results.

And in their own experiments, they managed to obtain the same level of degradation as reported in the study, using a mix of egg yolk and ground pork.

"While the biodegradation of mostly inert artificial polymers is definitely a very interesting research field, we must respectfully disagree with the methodology and conclusions from this paper," the German team wrote.

Their findings were published in the journal Current Biology, which also printed the original study.

The authors of the original study have not responded to a request for comment.

Explore further: Caterpillar found to eat shopping bags, suggesting biodegradable solution to plastic pollution

More information: Carina Weber et al. Polyethylene bio-degradation by caterpillars?, Current Biology (2017). DOI: 10.1016/j.cub.2017.07.004

Related Stories

No microbes? No problem for caterpillars

August 22, 2017

The microbiome seems ubiquitous: humans and many other species rely on billions of tiny organisms in their guts to aid in digestion, metabolism and other functions. Now, scientists at the University of Colorado Boulder are ...

Gut bacteria from a worm can degrade plastic

December 3, 2014

Plastic is well-known for sticking around in the environment for years without breaking down, contributing significantly to litter and landfills. But scientists have now discovered that bacteria from the guts of a worm known ...

Chewing gum improves colonoscopy preparation

February 22, 2016

(HealthDay)—Chewing gum relieves discomfort associated with ingestion of the polyethylene glycol solution for colonoscopy preparation, according to a study published in the February issue of the Journal of Clinical Nursing.

Recommended for you

DNA islands effective as 'anti-bacterial drones'

September 24, 2018

Genomic "islands" that evolved from viruses can be converted into "drones" that disable Staphylococcus aureus, bacteria that are often resistant to antibiotics and pose a threat to safe hospital care, a new study finds.

Custom circuits for living cells

September 24, 2018

A team of Caltech researchers has developed a biological toolkit of proteins that can be assembled together in different ways, like Legos, to program new behaviors in cells. As a proof-of-concept, they designed and constructed ...

Burst of morning gene activity tells plants when to flower

September 24, 2018

For angiosperms—or flowering plants—one of the most important decisions facing them each year is when to flower. It is no trivial undertaking. To flower, they must cease vegetative growth and commit to making those energetically ...

Silver fox study reveals genetic clues to social behavior

September 24, 2018

In 1959, Russian scientists began an experiment to breed a population of silver foxes, selecting and breeding foxes that exhibited friendliness toward people. They wanted to know if they could repeat the adaptations for tameness ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.